- Email: [email protected]
Daytime intrusive thoughts and subjective insomnia symptoms
Author's Accepted Manuscript
Daytime intrusive thoughts and subjective insomnia symptoms Louise D. Baker, David S. Baldwin, Matthew Garner
www.elsevier.com/locate/psychres
PII: DOI: Reference:
S0165-1781(15)00151-1 http://dx.doi.org/10.1016/j.psychres.2015.02.022 PSY8812
To appear in:
Psychiatry Research
Received date: 25 April 2014 Revised date: 28 January 2015 Accepted date: 14 February 2015 Cite this article as: Louise D. Baker, David S. Baldwin, Matthew Garner, Daytime intrusive thoughts and subjective insomnia symptoms, Psychiatry Research, http://dx.doi.org/10.1016/j.psychres.2015.02.022 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Title Page
Daytime intrusive thoughts and subjective insomnia symptoms
Louise D. Baker a, *, David S. Baldwin b, Matthew Garner a, b,*
a
Psychology, Faculty of Social and Human Sciences, University of Southampton, Southampton, SO17,
1BJ, UK b
Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton,
SO17, 1BJ, UK Address: Psychology, Faculty of Social and Human Sciences, University of Southampton, Southampton, SO17 1BJ, UK. Tel: +44 (0) 23 80595926
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Abstract Insomnia is increasingly recognized as a 24 hour complaint that is associated with an increased risk of mood and anxiety disorders. However, the effects of insomnia symptoms on maladaptive daytime patterns of thinking are poorly understood. We examined the relationship between subjective insomnia symptoms, attentional control and negative thought intrusions during daytime in a large sample of undergraduates experiencing poor sleep. A total of 109 participants completed self-report measures of sleep quality, current sleepiness, anxiety and attentional control. A behavioural measure of intrusive thought required participants to control their attention during two focus periods separated by a fiveminute period of self-referential worry. Thought intrusions were sampled throughout the pre- and postworry periods. Perceived insomnia severity was associated with the reduced ability to focus attention and uniquely associated with increased negative thought intrusions in the pre-worry period. These results support suggestions that acute episodes of poor sleep can dysregulate key networks involved in attentional control and emotion regulation, and that promote negative cognitive activity.
Key words: Insomnia symptoms, daytime dysfunction, distractibility
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
1. Introduction Historically, insomnia has been characterised as “the result of an inability to turn off intrusive, affectively-laden thoughts and images at bedtime” (Borkovec et al., 1983, p.9). Whilst this definition captures the important nocturnal aspect of insomnia, the evidence base for parallel daytime processes is increasing, and supports the reconceptualization of insomnia as a ‘24 hour disorder’ (International Classification of Sleep Disorders, 2nd edition, 2005; Diagnostic and Statistical Manual of Mental Disorders, 4th edition., text revision, 2000). Worrisome thought is a central feature of several models of insomnia maintenance (e.g. Espie, 2002; Harvey, 2002; Lundh and Broman, 2000; Morin, 1993) and involves persistent intrusive thought; “spontaneous, unwanted, unbidden, uncontrollable and discrete thoughts attributed to an internal origin” (Rachman, 1981; Wells and Morrison 1994 cited in Harvey, Tang and Browning, 2005, p.599). The characteristics and consequences of nocturnal negative cognitive hyperactivity are well known (Harvey, 2002), however the relationship between insomnia symptoms and daytime cognitive hyperactivity (specifically thought intrusions and worry) has not been examined. It is important to determine whether acute episodes of sleep disturbance are associated with daytime cognitive dysfunction because clarifying the processes involved in the transition from poor sleep to chronic insomnia has been highlighted as a priority in order to improve treatment for the condition (Ellis et al., 2012). Sleep-related worry has been investigated as a process variable within cognitive behavioural therapy for insomnia (CBT-I) which may improve key symptoms (self-reported insomnia severity, total sleep time and wake after sleep onset) (Sunnhed and Jansson-Frőjmark, 2014). However, it is unclear whether more general, intrusive negative cognition is also a feature of insomnia symptoms (which includes sub-clinical levels of poor sleep and concern about daytime function) that should be targeted early on in the complaint. Consistent with evidence that distractability (‘mindwandering’) is a dominant predictor of negative affect (Killingsworth and Gilbert, 2010), the experience of poor cognitive control and thought intrusions in poor sleepers might confer risk for comorbid mood and anxiety disorder. Accordingly we investigated the frequency and valence of thought intrusions in a sample of young adults who naturally and markedly vary in their sleep quality. Young adults are a comparatively neglected population in sleep research yet it has been reliably demonstrated that insomnia symptoms are important in this population and more complex than patterns of (voluntary) sleep restriction associated with lifestyle factors. In Taylor et al. (2013), 33.4% of 1,039 students reported insomnia symptoms and a further 9.5% reported chronic insomnia (according to DSMV criteria, sleep diaries and self-report measures). Lund et al. (2010) found 60% of 1,125 university students were ‘poor sleepers’ according to the Pittsburgh Sleep Quality Index (PSQI), with academic stress and emotional upheaval the most common causes of sleep trouble (39% and 25% respectively). *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Stress and tension accounted for the most variance in PSQI scores (24%), e.g. ‘stress about college’ ‘racing thoughts’ and ‘worry about the future,’ suggesting the importance of thought intrusions and repetitive thought in this population. We measured the frequency and valence of thought intrusions using an established measure of thought intrusions developed by Ruscio and Borkovec (2004) and adapted by Hirsch et al., (2009). This task has been widely used to examine thought intrusions and worry in non-clinical groups (Krebs et al., 2010), individuals with elevated worry, and generalised anxiety disorder (Hayes et al., 2010; Hirsch et al., 2009). The thought intrusions task measures the occurrence of resting level, spontaneously occurring thoughts which distract from the current task. It further measures the pervasiveness of thought intrusions following a period of active worry on a topic chosen by the participant. This paradigm overcomes limitations associated with self-report questionnaires that ask participants to retrospectively report the frequency with which they worry about a pre-determined set of topics chosen by researchers, and that might be confounded by recall bias. Our study is the first to test the hypothesis that insomnia symptoms in young adults are associated with greater daytime thought intrusions, in particular negative thought intrusions, at baseline and following a period of self-referent worry. These predictions are consistent with previous evidence that cognitive control of attention is fundamentally affected following disturbed sleep and that worry is a central component of insomnia maintenance. We assessed the uniqueness of this relationship beyond the effects of anxiety and self-report deficits in cognitive control, both of which have been suggested to be elevated in insomnia, and associated with negative thought intrusions.
2. Method 2.1 Participants Participants were 109 (82% F) university students with a mean age of 20.70 years (SD= 4.56) who received course credits for participation. Participants responded to an online advertisement for ‘a study investigating sleep and daytime function’ – all respondents were invited to participate. Written informed consent was taken prior to participation. All study procedures were reviewed and approved by the University of Southampton Ethics Committee and the Research Governance Office. 2.2 Design and Procedure. A cross-sectional research design examined associations between thought intrusions measured by the BTF and widely used self-report measures of insomnia severity (Insomnia Severity Index – ISI) and poor sleep quality (Pittsburgh Sleep Quality Index – PSQI), details below. Secondary self-report measures of attentional control (Attention Control Scale - ACS), trait anxiety (trait version of the Spielberger Anxiety Inventory, STAI) and current sleepiness were also included. *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
2.3 Measures of subjective insomnia symptoms and sleep quality 1) Insomnia Severity Questionnaire (ISI, Bastien et al., 2001).The ISI measures perceived severity of insomnia, which corresponds with DSM-IV criteria for insomnia. It measures degree of satisfaction with sleep, interference with daytime function, noticability of impairment and distress associated with the complaint. Responses are made on a 0-4 scale with higher scores reflecting a greater problem over the past two weeks. According to previously published guidelines for nonclinical populations a cut-off score of 10 identifies clinically important insomnia (Morin et al., 2011) with 86% sensitivity and 87.7% specificity. The scale has good internal consistency and test-retest reliability (Bastien et al., 2001), with a Cronbach’s α of 0.84 in the current study. 2) Pittsburgh Sleep Quality Index (PSQI, Buysse, et al.,1989). The PSQI measures sleep quality over the past month measuring several key aspects of a poor sleep complaint; sleep quality, latency, disturbance, duration, habitual sleep efficiency, medication use and related daytime dysfunction. Responses are made on a 0-3 subscale to reflect the majority of days and nights. Scores range from 0-21 where a cut-off score of 5 achieves maximum specificity and sensitivity for detecting insomnia. The measure has strong internal validity (α = 0.83) and temporal stability (α = 0.85 for an average of 28.2 days) (Buysse et al., 1989) with a Cronbach’s α of 0.75 in this study. 3) Spielberger Stait-Trait Anxiety Inventory (STAI-T, Spielberger et al., 1983). The STAI-T is a selfreport measure of anxiety as a general disposition. It comprises 20 items which participants rate on 0- 4 point scale with a possible range from 20 to 80 where higher scores reflect higher anxiety. The scale has high test-retest reliability and internal reliability α = 0.86 (Barnes et al., 2002), with a Cronbach’s α of 0.93 in this study. 4)
Stanford Sleepiness Scale (SSS, Hoddes et al., 1973). The SSS measures moment-to-moment sleepiness which is affected by a whole range of contextual factors including propensity for sleep, sensory stimulation, motivation, hunger/ thirst and posture (Dement and Carskadon, 1982). The measure has a 7-point scale where 1 is “Feeling active, vital, alert or wide awake” and 7 is “No longer fighting sleep, sleep onset soon; having dream-like thoughts.” A score greater than 3 indicates significant sleepiness. We included a measure of sleepiness because daytime sleepiness (reflecting sleep debt) is considered to be a key marker of acute sleep loss (and associated acute rather than chronic insomnia symptoms) in this population.
5) Attentional Control Scale (ACS, Derryberry and Reed, 2002). The ACS is a trait measure of attention control, specifically the ability to ‘focus’, or maintain attention on a given task, and the ability to ‘shift’, or redirect attention to a new stimulus or between multiple competing tasks. There are 20 items rated on a 4-point scale where higher scores indicate better attentional control and the range is 20-80. Cronbach’s α of 0.75 in this sample.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
2.4 The thought intrusions task Consistent with Hirsch et al. (2009) the thought intrusions task contained three stages; an initial 5 minute breathing focus, a five-minute worry period and a five-minute post-worry breathing focus. During pre-worry and post-worry breathing focus periods participants were instructed to focus attention on their breathing. If thoughts wandered away from their breath participants were instructed to redirect attention back to their breathing. Within pre- and post-worry periods 12 beeps were presented (between 20-30 seconds apart). On hearing a beep participants were asked to state one of four response options; if focussing on their breath as instructed, then participants reported “Breathing”. However if when probed their attention had wandered from their breath, then they briefly described the content of the thought, and whether it was positive, negative or neutral (e.g. “Looking forward to seeing my friends; positive”, “Worried I won’t meet my deadline; negative”). The experimenter logged all thought intrusions as they occurred and confirmed the reported valence with the participant at the end of the study. In between breathing-focus periods participants were asked to identify a current worry. This was briefly discussed with the experimenter to ensure that the worry was characterised by concern about a future event (rather than a retrospective depressive concern). Over 50% of our sample identified a current worry related to workload, deadlines or exam pressure. Other worries included finance, relationships and change of residence. No sleep-related worries were chosen by participants. Participants rated (0-100) their worry with respect to i) how likely is this to happen? (Extremely unlikely to extremely likely), ii) how catastrophic would it be? (Not at all catastrophic to Extremely catastrophic), and iii) How well do you think you would cope? (Not at all well to Extremely well). Across the sample VAS ratings confirmed that the self-referential worry topics chosen by participants involved high levels of uncertainty as to likelihood of outcome (M=50.83, SD=21.00), would be moderately catastrophic (M=54.74, SD=25.09), and difficult to cope with (M=43.66, SD=22.49). Participants focused on the worry for five minutes. The key dependent measures from this task were mutually exclusive; number of breathing focuses (assessing maintenance of attention on task goal) and number and valence of thought intrusions (assessing distractibility and worrisome thought). Participants completed the ISI, PSQI, ACS and STAI two days prior to attending a test session in which they completed the sleepiness measure (SSS) and the thought intrusions task. Following standardised instructions (see Hirsch et al., 2010) participants completed a practice breathing focus trial that lasted 45 seconds and contained three thought sampling beeps, and the thought intrusions task in full. As part of the debrief participants read some amusing news stories to reduce any residual negative effects of the worry induction.
3. Results *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Descriptive statistics for all self-report measures are presented in Table 1. 36.8% the sample experienced clinically important insomnia symptoms over the past two weeks. According to the PSQI, 72.1% of the sample was classified as “poor-sleepers.” Average bedtime was 12.39 am (SD=1.19), average sleep onset latency was 33 minutes (SD=26.5) where the most commonly reported reason was ‘worry’/ ‘racing thoughts’, average rise time was 9.20 am (SD=1.85) and average hours of actual sleep was 7.53 (SD=1.38) (7.4% reported ≤ 5 hours, 9.3% reported 5-6 hours, 29.6% reported 6-7hours, 25.9% reported between 7-8 hours). Levels of trait anxiety, attentional control, and current sleepiness fell within the normal range (e.g. Alapin et al., 2000; Derryberry and Reed, 2001; Taylor et al., 2005). Participant gender did not interact with findings reported below, nor did the extent to which participants considered themselves to be predominantly morning or evening types (as measured by the Morningness-Eveningness Questionnaire (Horne & Östberg, 1976). 3.1 Associations between sleep quality, trait anxiety, attention control and sleepiness. Subjective poor sleep (PSQI) and insomnia severity (ISI) were strongly associated with increased trait anxiety, reduced attention control and increased sleepiness. Associations with poor sleep were driven by notable effects of sleep quality (PSQI), sleep disturbance (PSQI) and daytime symptoms (PSQI and ISI). Descriptive statistics for all self-report measures are presented in Table 1. As expected following the worry period (compared to pre-worry) participants were less able to focus on their breathing [premean = 8.72 (SD = 1.75), post-mean = 8.38 (SD = 2.15), t (108)=2.61, p<0.05], more likely to experience negative thought intrusions [pre-mean = 0.90, (SD = 1.1), post-mean = 1.58 (SD = 1.44), t (108) = 4.90, p<0.001], and less likely to experience positive thought intrusions [pre-mean = 1.25 (SD = 1.23), postmean = 0.83 (SD = 1.08), t (108)=3.49, p<0.01]. Likewise the worry period increased subjective feelings of worry (pre-worry= 20.33, post-worry = 42.67), t (106)= 7.79, p<0.001) and anxiety (pre-anxiety = 17.04, post-anxiety = 35.39, t (106)= 8.18 , p<0.001). We observed typically high levels of agreement between participant subjective ratings and experimenter ratings of thought valence [0.85 < r’s < 0.92]. The primary analysis of subjective valence ratings below is comparable with an equivalent analysis of experimenter valence ratings. 3.2 Associations between sleep quality, anxiety, attention control and thought intrusions at baseline During the pre-worry period the frequency of thought intrusions (across valence) was positively associated with nocturnal symptoms (ISI), sleep disturbance (PSQI) and daytime sleepiness due to poor sleep (PSQI). Trait anxiety was not significantly correlated with overall thought intrusions during the preworry period.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Frequency of negative thought intrusions was positively associated with subjective insomnia symptom severity (ISI_total) and poor sleep quality (PSQI_total), and also associated with trait anxiety and current sleepiness. Follow-up partial correlations confirmed that poor sleep was significantly associated with negative thought intrusions beyond the effect of current sleepiness (ISI: r =0.21, p=0.03, PSQI: r =0.23, p=0.02) and trait anxiety (ISI: r =0.20, p=0.04, PSQI: r =0.23, p=0.02). Supplementary regression analysis investigated whether specific sleep symptoms (quality, disturbance, daytime dysfunction) accounted for the observed associations between overall poor sleep and negative thought intrusions, however, there were no significant individual predictors within the model (F (3, 103)=3.64, p=0.02). Self-report attentional control was unrelated to the ability to focus on breathing. Self-report measures were unrelated to positive and neutral thought intrusions in this period. 3.3. Associations between sleep quality, anxiety, attention control and thought intrusions following worry. Following the five-minute worry period the frequency of thought intrusions remained positively associated with poor sleep quality (disturbance) and daytime sleepiness due to poor sleep, and in addition was further associated with insomnia severity and trait anxiety. Partial correlations confirmed that insomnia severity was not associated with greater thought intrusions, beyond the effect of anxiety (ISI: r =-0.11, p=0.27). Contrary to findings in the pre-worry (baseline) period, there were no significant associations between negative thought intrusions and measures of poor sleep. Instead, frequency of negative thought intrusions remained strongly associated with trait anxiety, and further associated with reduced self-report attention control and greater daytime sleepiness. A partial correlation confirmed that trait anxiety was associated with greater negative thought intrusions when controlling for baseline negative thought intrusions (r=0.32, p<0.01).
4. Discussion The role of thought intrusions in insomnia is poorly understood and limited to broad discussions of cognitive hyperactivity and negative cognitive activity in the pre-sleep period. Furthermore these observations have been primarily in those with clinical insomnia and where confounding variables (such as comorbid mood and anxiety disorder) might mask associations between poor sleep and thought intrusions. This is the first study to examine on-line, daytime intrusive thought and insomnia symptoms using the thought intrusions task. We revealed unique, positive associations between insomnia symptoms (over the past month) and negative thought intrusions at baseline (prior to explicitly activating worry). Night-time and daytime aspects of poor sleep contributed equally to this relationship, suggesting that negative thought intrusions are related to both sleep disturbance and its daytime consequences in this *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
population, beyond the current level of reported sleepiness. Consistent with previous findings (Hirsch et al., 2009), the worry period increased feelings of anxiety and worry, increased negative thought intrusions and reduced breathing focus. Trait anxiety and self-report attention control (but not sleep measures) were strongly associated with negative thought intrusions following the period of active worry. Why might sleep quality be associated with increased negative thought intrusions in the pre (but not post) worry period, whereas anxiety is more strongly associated with negative intrusions after a period of worry? It is likely that the worry period activated concerns that were particularly salient for those with elevated trait anxiety, and which remained primed for re-activation during the post-worry breathing focus period (consistent with classification systems that emphasise persistent worry as a core symptom of generalized anxiety disorder e.g. DSM-V, 2013). Conversely disturbed sleep was associated with the spontaneous activation of negative thoughts (in the pre-worry period), with broader difficulties focussing attention (post-worry) driven by co-occurring generalized anxiety. We also revealed significant negative associations between both night-time and daytime aspects of insomnia and the ability to focus and maintain attention on breathing at baseline (however, these associations were only observed for disturbance and daytime sleepiness components of the PSQI and night-time symptoms of the ISI). Surprisingly, we did not find an association with trait anxiety. Following the worry period, associations between insomnia severity and breathing focus were strengthened, as too were associations with trait anxiety. These results highlight the high level of shared variance between anxiety, poor sleep, and broader deficits in attention control. This is consistent with evidence that anxiety is associated with poor sleep in clinical samples, and that beyond worry, ruminative thinking (not measured here) might be an important additional feature of sleep disturbance (Carney, Harris, Moss and Edinger, 2010). Interestingly, we did not find associations between self-reported attentional control and breathing focus/negative thought intrusions at baseline, although these were revealed in the post-worry breathing period. The ACS asks individuals to report on their ability to control attention in situations where it may be challenged, e.g. “When I am working hard on something I still get distracted by events around me”. Thus associations between self-report ACS and behavioural measures of attention control (e.g. thought intrusions) might occur only during conditions of high cognitive load/distractibility e.g. following a period of active worry. The results of this study are important for several reasons. Using a novel experimental task we observed that more frequent thought intrusions (particularly negative intrusions) were associated with insomnia symptoms in young adults who commonly experience alterations to sleep environment, shifts to the timing of sleep onset and acute stress (Roth and Roehers, 2003). Due to environmental and biopsychosocial factors such as ineffective coping with sleep disturbance (Yang, Wu, Hseih, Liu and Lu, *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
2003) and increased exposure to sleep interfering events, this population is ‘at risk’ for development of persistent insomnia. Spontaneous intrusive thought, therefore, may be an important aspect of daytime dysfunction which is uniquely associated with insomnia symptoms and may result in a reduced ability to complete daytime tasks efficiently and exacerbate existing mood and anxiety problems during stressful periods. Results are consistent with findings from acute sleep deprivation studies that reveal dysfunction in key emotion neural networks implicated in emotion activation (e.g. amygdala) and regulation (e.g. prefrontal-cortex) following sleep loss (Tempesta et al., 2010; Yoo et al., 2007). They are also consistent with aetiological models of insomnia which consider heightened cognitive arousal as important within insomnia development. Finally, results show that in a ‘poor-sleeping’ population, daytime intrusive thoughts are not characterised by sleep-related concerns, as is commonly observed in clinical populations, but rather by broader concerns that relate to a range of current stressors. There are several limitations to this study. Firstly, the findings relate to intrusive thought in an undergraduate population that has unique sleep characteristics - students may be more able than other sleep-disturbed groups to compensate for sleep loss during the daytime (through napping, delayed rise time). Secondly, the cross-sectional nature of this study means that we cannot infer causation between poor sleep, negative thought intrusions and weakened attentional control. Thirdly, we did not include sleep diaries or an objective measure of sleep (e.g. actigraphy) to corroborate self-assessments of sleep quality. Fourthly, although we have discussed the possibility of negative thought intrusions as a risk factor for an escalating insomnia complaint, the cross-sectional design means that we cannot discriminate between factors which may predispose to poor-sleep, those which may perpetuate poor sleep, and those which arise from an acute poor-sleep episode. Nevertheless, by assessing sleep over the past month in non-treatment seeking individuals, it is likely that we predominantly measured initial acute sleep disturbance. The thought intrusions task provided a sensitive measure of daytime thought intrusions in a poor sleeping population, before and after a period of worry. Thought samples were spontaneous and unique at the level of the individual, overcoming limitations of previous analogue studies which used a standardised stressor to evoke state worry (i.e. speech threat) in order to measure associated cognitive activity. This study is novel and requires replication within other poor-sleeping populations, including those with a clinical sleep disorder. Future studies could extend the use of this task to profile thought intrusions across varying levels of poor sleep/insomnia severity in order to test theories relating to the development of insomnia which emphasise the increasing importance of sleep-related worry (Espie, 2002; Harvey 2002). Furthermore, in line with emerging evidence that attention training towards benign appraisals of threatening stimuli can reduce worry and anxiety in high-worriers (Hirsch et al., 2009), the *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
thought intrusions task may be useful within CBT-I as an outcome tool for measuring change to sleeprelated attentional bias, which is a reliable feature of insomnia disorder (Marchetti et al., 2006). Currently, our understanding of factors involved in the transition from poor sleep to chronic insomnia is limited. Our finding that negatively valenced thought intrusions and poor attentional control are associated with poor sleep/acute insomnia, highlights the potential importance of this mechanism in the development of sleep disorders.
Acknowledgements: Megan Wingfield, Jade Lymn, Louise Kenny and Robin Wickens for their help with data collection. Contributors: LB undertook management of the study, collected and analysed data and led drafting of the paper. MG and DB supported management of the study, analysis and drafting of the paper. Conflict of Interests: LB has no conflict of interests. MG has received support from Eli Lilly to attend scientific conferences and has held research grants from Lundbeck and Pfizer Ltd. On behalf of his employer DSB has held research grants from Bristol-Myers Squibb, Cephalon, Eli Lilly Ltd, GlaxoSmithKline, H. Lundbeck A/S, Pierre Fabre, Pfizer Ltd, Roche and Vernalis Ltd. He has served on advisory boards hosted by Astra-Zeneca, Bristol-Myers Squibb, Eli Lilly Ltd, GlaxoSmithKline, Grunenthal, H. Lundbeck A/S, Pierre Fabre, and Pfizer Ltd. He is a past President of Depression Alliance and a current Medical Patron of Anxiety UK.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
References Alapin, I., Fichten, C. S., Libman, E., Creti, L., Bailes, S., Wright, J., 2000. How is good and poor sleep in older adults and college students related to daytime sleepiness, fatigue, and ability to concentrate? Journal of Psychosomatic Research 49, 381-390. American Academy of Sleep Medicine, 2005. The International Classification of Sleep Disorders: Diagnostic & Coding Manual, 2nd ed. American Academy of Sleep Medicine, Westchester, IL. American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. text revision. American Psychiatric Association, Washington, DC. American Psychiatric Association, 2013. Diagnostic and Statistical Manual of Mental Disorders, 5th ed. American Psychiatric Association, Washington, DC. Barnes, L. L. B., Harp, D, Jung, W. S., 2012. Reliability generalization of scores on the Spielberger StateTrait Anxiety Inventory. Educational and Psychological Measurement 62, 603–618. *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Bastien, C.H., Vallieres, A., Morin, C., 2001. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Medicine 2, 297-306. Borkovec, T. D., Lane, T. W., VanOot, P. H., 1981. Phenomenology of sleep among insomniacs and good sleepers: Wakefulness experience when cortically asleep. Journal of Abnormal Psychology 90, 607- 609. Borkovec, T. D., Robinson, E., Pruzinsky, T., DePree, J. A., 1983. Preliminary exploration of worry: Some characteristics and processes. Behaviour Research Therapy 21, 9–16. Buysse D. J, Reynolds, C.F., Monk, T.H., Berman, S.R., Kupfer, D.J., 1989. The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research. Psychiatry Research 28, 193–213. Carney, C.E., Harris, A.L., Moss, T.G., Edinger, J.D. (2010). Distinguishing rumination from worry in clinical insomnia. Behaviour Research and Therapy 48, 540–546 Dement, W.C., Carskadon, M.A., 1982. An essay on sleepiness. In: Baldy-Moulinier, M. (Ed.) Actualites en Medicine Experimentale: En Homage au Proffeseur P. Passouant. Euromed, Montpellier, France, pp. 47-71. Derryberry, D., Reed, M. A., 2002. Anxiety-related attentional biases and their regulation by attentional control. Journal of Abnormal Psychology 111, 225–236. Ellis, J. G., Gehrman, P., Espie, C., Riemann, D., Perlis, M. L. 2012. Acute insomnia: Current conceptualizations and future directions. Sleep Medicine Reviews 16, 5–14. Espie CA. (2002). Insomnia: conceptual issues in the development, persistence, and treatment of sleep disorders in adults. Annual. Review of Psychology 53, 215–243. Hall, M., Buysse, D. J., Reynolds, C. F., Kupfer, D. J., Baum, A., 1994. Stress-related intrusive thoughts disrupt sleep onset and continuity. Sleep Research 25, 163. Harvey, A. G., 2002. A cognitive model of insomnia. Behaviour. Research and Therapy 40, 869-893. Harvey, A.G., 2005. Unwanted intrusive thought in insomnia. In: Clark, D.A. (Ed.) Intrusive Thought in Clinical Disorders. Guilford Press, New York, pp.30-53. Harvey, A. G., Payne, S., 2002. The management of unwanted pre-sleep thoughts in insomnia: distraction with imagery versus general distraction. Behaviour Research and Therapy 40, 267–277. *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Harvey, A. G., Tang, N. K. Y., Browning, L. 2005. Cognitive approaches to insomnia. Clinical Psychology Review, 25, 593–611. Hayes, S., Hirsch, C.R., Mathews, A., 2010. Facilitating a benign attentional bias reduces negative thought intrusions. Journal of Abnormal Psychology 119, 235–240. Hirsch, C. R., Hayes, S., Mathews, A., 2009. Looking on the bright side: accessing benign meanings reduces worry. Journal of Abnormal Psychology 118, 44-54. Hoddes, E., Zarcone, V., Smythe, H., Phillips, R., Dement, W.C., 1973. Quantification of sleepiness: a new approach. Psychophysiology 10, 431–437. Horne, J. A., Östberg, 0. (1976). A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology 4, 97-l10. Killingsworth M. A., Gilbert D. T., 2010. A wandering mind is an unhappy mind. Science 330, 932–932. Krebs, G., Hirsch, C.R., Mathews, A., 2010. The effect of attention modification with explicit versus minimal instructions on worry. Behaviour Research and Therapy 48, 251–256. Lund, H. G., Reider, B. D., Whiting, A. B., Prichard, J. R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. Journal of Adolescent Health 46, 124–132. Lundh, L. G., Broman, J. E., 2000. Insomnia as an interaction between sleep-interfering and sleepinterrupting processes. Journal of Psychosomatic Research 49, 299–310. Marchetti, L. M., Biello, S. M., Broomfield, N.M., MacMahon, K.M., Espie C.A., 2006. Who is preoccupied with sleep ? A comparison of attention bias in people with psychophysiological insomnia, delayed sleep phase syndrome and good sleepers using the induced change blindness paradigm. Journal of Sleep Research 15, 212–221. Morin, C., 1993. Insomnia: Psychological Assessment and Management. Guilford Press, New York. Morin, C. M., Belleville, G., Bélanger, L., Ivers, H., 2011. The Insomnia Severity Index: psychometric indicators to detect insomnia cases and evaluate treatment response. Sleep, 34, 601–608. Roth, T., Roehrs, T., 2003. Insomnia: Epidemiology, characteristics, and consequences. Clinical Cornerstone 5, 5-15.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Ruscio, A. M., Borkovec, T. D., 2004. Experience and appraisal of worry among high worriers with and without generalized anxiety disorder. Behaviour Research and Therapy 42, 1469–1482. Spielberger, C.D. Gorusch, R.L., Lushene, R., Vagg, P.R., Jacobs, G.A., 1983. Manual for the State-Trait Anxiety Inventory (Form Y). Consulting Psychologists Press, Palto Alto, CA. Sunnhed, R., Jansson-Fröjmark, M., 2014. Are changes in worry associated with treatment response in cognitive behavioral therapy for insomnia? Cognitive Behaviour Therapy 43, 1-11. Taylor, D. J., Bramoweth, A. D., Grieser, E., Tatum, J. I., Roane, B. M. (2013). Epidemiology of insomnia in college students: relationship with mental health, quality of life, and substance use difficulties. Behavior Therapy 44, 339–348. Taylor, D.J., Lichstein, K.L., Durrence, H.H., Reidel, B.W., Bush, A.J., 2005. Epidemiology of insomnia, depression, and anxiety. Sleep 28, 1457–1464. Tempesta, D., Couyoumdjian, A., Curcio, G., 2010. Lack of sleep affects the evaluation of emotional stimuli. Brain Research Bulletin 82, 104–108. Wells, A., Morrison, A. P., 1994. Qualitative dimensions of normal worry and normal obsessions: A comparative study. Behaviour Research and Therapy 32, 867-870. Yoo, S-S, Gujar, N., Hu, P., Jolesz, F. A., Walker, M. P., 2007. The human emotional brain without sleep — a prefrontal amygdala disconnect. Bipolar Disorders 17, 877-878.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Table 1: Sample characteristics and associations between subjective sleep, anxiety and thought intrusions.
SSS
ACS
STAI
Baseline
Baseline
Post-worry
Post-worry
breathing
negative
breathing
negative
focus
intrusions
focus
intrusions
M
SD
ISI total
8.21
4.50
0.28**
-0.28**
0.47**
-0.18 (.06)
0.25**
-0.21*
0.19 (.05)
Daytime
5.15
3.00
0.28**
-0.32**
0.54**
-0.14
0.20*
-0.18
0.14
Nighttime
3.06
1.98
0.19
-0.15
0.27**
-0.20**
0.27**
-0.20
0.13
PSQI total
6.55
3.18
0.31**
-0.27**
0.47**
-0.16
0.26**
-0.14
0.13
Quality
1.26
0.68
0.28**
-0.24*
0.35**
-0.10
0.27**
-0.02
0.05
Disturbance
1.23
0.47
0.24*
-0.26**
0.45***
-0.22*
0.22*
-0.22*
0.13
Latency
1.58
0.87
0.23*
-0.13
0.19
-0.05
0.14
-0.06
0.17
Duration
0.29
0.63
0.05
-0.01
0.19
-0.17
0.18
-0.15
0.14
Efficiency
0.87
1.03
0.17
-0.13
0.34**
-0.09
0.16
-0.11
0.02
Medication
0.17
0.49
0.31**
-0.02
0.06
-0.05
-0.04
0.06
0.04
Daytime
1.15
0.71
0.31**
-0.42**
0.54***
-0.28**
0.20*
-0.20*
0.19*
SSS
3.03
0.90
-
-0.29**
0.33**
0.08
0.23*
-0.10
0.14
ACS
47.78
8.43
-
-
-0.57***
0.13
-0.12
0.20*
-0.40**
STAI
40.17
10.54
-
-
-
-0.15
0.21*
-0.21*
0.37**
dysfunction
NB: Scores in parentheses are p-values that reflect statistical trends that fall short of the conventional significance threshold p<0.05. ISI; Insomnia Severity Index, PSQI; Pittsburgh Sleep Quality Index; SSS; Stanford Sleepiness Scale, ACS; Attentional Control Scale, STAI; Spielberger Trait Anxiety Inventory, *p<0.05, **p<0.01***, p<0.001.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Highlights First study of association between insomnia symptoms and daytime intrusive thoughts. Insomnia symptoms predicted subjective and behavioural measures of thought control. Insomnia symptoms were uniquely associated with negative thought intrusions. We highlight thought control/intrusions as a therapeutic target in early insomnia.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Daytime intrusive thoughts and subjective insomnia symptoms Louise D. Baker, David S. Baldwin, Matthew Garner
www.elsevier.com/locate/psychres
PII: DOI: Reference:
S0165-1781(15)00151-1 http://dx.doi.org/10.1016/j.psychres.2015.02.022 PSY8812
To appear in:
Psychiatry Research
Received date: 25 April 2014 Revised date: 28 January 2015 Accepted date: 14 February 2015 Cite this article as: Louise D. Baker, David S. Baldwin, Matthew Garner, Daytime intrusive thoughts and subjective insomnia symptoms, Psychiatry Research, http://dx.doi.org/10.1016/j.psychres.2015.02.022 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Title Page
Daytime intrusive thoughts and subjective insomnia symptoms
Louise D. Baker a, *, David S. Baldwin b, Matthew Garner a, b,*
a
Psychology, Faculty of Social and Human Sciences, University of Southampton, Southampton, SO17,
1BJ, UK b
Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton,
SO17, 1BJ, UK Address: Psychology, Faculty of Social and Human Sciences, University of Southampton, Southampton, SO17 1BJ, UK. Tel: +44 (0) 23 80595926
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Abstract Insomnia is increasingly recognized as a 24 hour complaint that is associated with an increased risk of mood and anxiety disorders. However, the effects of insomnia symptoms on maladaptive daytime patterns of thinking are poorly understood. We examined the relationship between subjective insomnia symptoms, attentional control and negative thought intrusions during daytime in a large sample of undergraduates experiencing poor sleep. A total of 109 participants completed self-report measures of sleep quality, current sleepiness, anxiety and attentional control. A behavioural measure of intrusive thought required participants to control their attention during two focus periods separated by a fiveminute period of self-referential worry. Thought intrusions were sampled throughout the pre- and postworry periods. Perceived insomnia severity was associated with the reduced ability to focus attention and uniquely associated with increased negative thought intrusions in the pre-worry period. These results support suggestions that acute episodes of poor sleep can dysregulate key networks involved in attentional control and emotion regulation, and that promote negative cognitive activity.
Key words: Insomnia symptoms, daytime dysfunction, distractibility
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
1. Introduction Historically, insomnia has been characterised as “the result of an inability to turn off intrusive, affectively-laden thoughts and images at bedtime” (Borkovec et al., 1983, p.9). Whilst this definition captures the important nocturnal aspect of insomnia, the evidence base for parallel daytime processes is increasing, and supports the reconceptualization of insomnia as a ‘24 hour disorder’ (International Classification of Sleep Disorders, 2nd edition, 2005; Diagnostic and Statistical Manual of Mental Disorders, 4th edition., text revision, 2000). Worrisome thought is a central feature of several models of insomnia maintenance (e.g. Espie, 2002; Harvey, 2002; Lundh and Broman, 2000; Morin, 1993) and involves persistent intrusive thought; “spontaneous, unwanted, unbidden, uncontrollable and discrete thoughts attributed to an internal origin” (Rachman, 1981; Wells and Morrison 1994 cited in Harvey, Tang and Browning, 2005, p.599). The characteristics and consequences of nocturnal negative cognitive hyperactivity are well known (Harvey, 2002), however the relationship between insomnia symptoms and daytime cognitive hyperactivity (specifically thought intrusions and worry) has not been examined. It is important to determine whether acute episodes of sleep disturbance are associated with daytime cognitive dysfunction because clarifying the processes involved in the transition from poor sleep to chronic insomnia has been highlighted as a priority in order to improve treatment for the condition (Ellis et al., 2012). Sleep-related worry has been investigated as a process variable within cognitive behavioural therapy for insomnia (CBT-I) which may improve key symptoms (self-reported insomnia severity, total sleep time and wake after sleep onset) (Sunnhed and Jansson-Frőjmark, 2014). However, it is unclear whether more general, intrusive negative cognition is also a feature of insomnia symptoms (which includes sub-clinical levels of poor sleep and concern about daytime function) that should be targeted early on in the complaint. Consistent with evidence that distractability (‘mindwandering’) is a dominant predictor of negative affect (Killingsworth and Gilbert, 2010), the experience of poor cognitive control and thought intrusions in poor sleepers might confer risk for comorbid mood and anxiety disorder. Accordingly we investigated the frequency and valence of thought intrusions in a sample of young adults who naturally and markedly vary in their sleep quality. Young adults are a comparatively neglected population in sleep research yet it has been reliably demonstrated that insomnia symptoms are important in this population and more complex than patterns of (voluntary) sleep restriction associated with lifestyle factors. In Taylor et al. (2013), 33.4% of 1,039 students reported insomnia symptoms and a further 9.5% reported chronic insomnia (according to DSMV criteria, sleep diaries and self-report measures). Lund et al. (2010) found 60% of 1,125 university students were ‘poor sleepers’ according to the Pittsburgh Sleep Quality Index (PSQI), with academic stress and emotional upheaval the most common causes of sleep trouble (39% and 25% respectively). *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Stress and tension accounted for the most variance in PSQI scores (24%), e.g. ‘stress about college’ ‘racing thoughts’ and ‘worry about the future,’ suggesting the importance of thought intrusions and repetitive thought in this population. We measured the frequency and valence of thought intrusions using an established measure of thought intrusions developed by Ruscio and Borkovec (2004) and adapted by Hirsch et al., (2009). This task has been widely used to examine thought intrusions and worry in non-clinical groups (Krebs et al., 2010), individuals with elevated worry, and generalised anxiety disorder (Hayes et al., 2010; Hirsch et al., 2009). The thought intrusions task measures the occurrence of resting level, spontaneously occurring thoughts which distract from the current task. It further measures the pervasiveness of thought intrusions following a period of active worry on a topic chosen by the participant. This paradigm overcomes limitations associated with self-report questionnaires that ask participants to retrospectively report the frequency with which they worry about a pre-determined set of topics chosen by researchers, and that might be confounded by recall bias. Our study is the first to test the hypothesis that insomnia symptoms in young adults are associated with greater daytime thought intrusions, in particular negative thought intrusions, at baseline and following a period of self-referent worry. These predictions are consistent with previous evidence that cognitive control of attention is fundamentally affected following disturbed sleep and that worry is a central component of insomnia maintenance. We assessed the uniqueness of this relationship beyond the effects of anxiety and self-report deficits in cognitive control, both of which have been suggested to be elevated in insomnia, and associated with negative thought intrusions.
2. Method 2.1 Participants Participants were 109 (82% F) university students with a mean age of 20.70 years (SD= 4.56) who received course credits for participation. Participants responded to an online advertisement for ‘a study investigating sleep and daytime function’ – all respondents were invited to participate. Written informed consent was taken prior to participation. All study procedures were reviewed and approved by the University of Southampton Ethics Committee and the Research Governance Office. 2.2 Design and Procedure. A cross-sectional research design examined associations between thought intrusions measured by the BTF and widely used self-report measures of insomnia severity (Insomnia Severity Index – ISI) and poor sleep quality (Pittsburgh Sleep Quality Index – PSQI), details below. Secondary self-report measures of attentional control (Attention Control Scale - ACS), trait anxiety (trait version of the Spielberger Anxiety Inventory, STAI) and current sleepiness were also included. *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
2.3 Measures of subjective insomnia symptoms and sleep quality 1) Insomnia Severity Questionnaire (ISI, Bastien et al., 2001).The ISI measures perceived severity of insomnia, which corresponds with DSM-IV criteria for insomnia. It measures degree of satisfaction with sleep, interference with daytime function, noticability of impairment and distress associated with the complaint. Responses are made on a 0-4 scale with higher scores reflecting a greater problem over the past two weeks. According to previously published guidelines for nonclinical populations a cut-off score of 10 identifies clinically important insomnia (Morin et al., 2011) with 86% sensitivity and 87.7% specificity. The scale has good internal consistency and test-retest reliability (Bastien et al., 2001), with a Cronbach’s α of 0.84 in the current study. 2) Pittsburgh Sleep Quality Index (PSQI, Buysse, et al.,1989). The PSQI measures sleep quality over the past month measuring several key aspects of a poor sleep complaint; sleep quality, latency, disturbance, duration, habitual sleep efficiency, medication use and related daytime dysfunction. Responses are made on a 0-3 subscale to reflect the majority of days and nights. Scores range from 0-21 where a cut-off score of 5 achieves maximum specificity and sensitivity for detecting insomnia. The measure has strong internal validity (α = 0.83) and temporal stability (α = 0.85 for an average of 28.2 days) (Buysse et al., 1989) with a Cronbach’s α of 0.75 in this study. 3) Spielberger Stait-Trait Anxiety Inventory (STAI-T, Spielberger et al., 1983). The STAI-T is a selfreport measure of anxiety as a general disposition. It comprises 20 items which participants rate on 0- 4 point scale with a possible range from 20 to 80 where higher scores reflect higher anxiety. The scale has high test-retest reliability and internal reliability α = 0.86 (Barnes et al., 2002), with a Cronbach’s α of 0.93 in this study. 4)
Stanford Sleepiness Scale (SSS, Hoddes et al., 1973). The SSS measures moment-to-moment sleepiness which is affected by a whole range of contextual factors including propensity for sleep, sensory stimulation, motivation, hunger/ thirst and posture (Dement and Carskadon, 1982). The measure has a 7-point scale where 1 is “Feeling active, vital, alert or wide awake” and 7 is “No longer fighting sleep, sleep onset soon; having dream-like thoughts.” A score greater than 3 indicates significant sleepiness. We included a measure of sleepiness because daytime sleepiness (reflecting sleep debt) is considered to be a key marker of acute sleep loss (and associated acute rather than chronic insomnia symptoms) in this population.
5) Attentional Control Scale (ACS, Derryberry and Reed, 2002). The ACS is a trait measure of attention control, specifically the ability to ‘focus’, or maintain attention on a given task, and the ability to ‘shift’, or redirect attention to a new stimulus or between multiple competing tasks. There are 20 items rated on a 4-point scale where higher scores indicate better attentional control and the range is 20-80. Cronbach’s α of 0.75 in this sample.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
2.4 The thought intrusions task Consistent with Hirsch et al. (2009) the thought intrusions task contained three stages; an initial 5 minute breathing focus, a five-minute worry period and a five-minute post-worry breathing focus. During pre-worry and post-worry breathing focus periods participants were instructed to focus attention on their breathing. If thoughts wandered away from their breath participants were instructed to redirect attention back to their breathing. Within pre- and post-worry periods 12 beeps were presented (between 20-30 seconds apart). On hearing a beep participants were asked to state one of four response options; if focussing on their breath as instructed, then participants reported “Breathing”. However if when probed their attention had wandered from their breath, then they briefly described the content of the thought, and whether it was positive, negative or neutral (e.g. “Looking forward to seeing my friends; positive”, “Worried I won’t meet my deadline; negative”). The experimenter logged all thought intrusions as they occurred and confirmed the reported valence with the participant at the end of the study. In between breathing-focus periods participants were asked to identify a current worry. This was briefly discussed with the experimenter to ensure that the worry was characterised by concern about a future event (rather than a retrospective depressive concern). Over 50% of our sample identified a current worry related to workload, deadlines or exam pressure. Other worries included finance, relationships and change of residence. No sleep-related worries were chosen by participants. Participants rated (0-100) their worry with respect to i) how likely is this to happen? (Extremely unlikely to extremely likely), ii) how catastrophic would it be? (Not at all catastrophic to Extremely catastrophic), and iii) How well do you think you would cope? (Not at all well to Extremely well). Across the sample VAS ratings confirmed that the self-referential worry topics chosen by participants involved high levels of uncertainty as to likelihood of outcome (M=50.83, SD=21.00), would be moderately catastrophic (M=54.74, SD=25.09), and difficult to cope with (M=43.66, SD=22.49). Participants focused on the worry for five minutes. The key dependent measures from this task were mutually exclusive; number of breathing focuses (assessing maintenance of attention on task goal) and number and valence of thought intrusions (assessing distractibility and worrisome thought). Participants completed the ISI, PSQI, ACS and STAI two days prior to attending a test session in which they completed the sleepiness measure (SSS) and the thought intrusions task. Following standardised instructions (see Hirsch et al., 2010) participants completed a practice breathing focus trial that lasted 45 seconds and contained three thought sampling beeps, and the thought intrusions task in full. As part of the debrief participants read some amusing news stories to reduce any residual negative effects of the worry induction.
3. Results *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Descriptive statistics for all self-report measures are presented in Table 1. 36.8% the sample experienced clinically important insomnia symptoms over the past two weeks. According to the PSQI, 72.1% of the sample was classified as “poor-sleepers.” Average bedtime was 12.39 am (SD=1.19), average sleep onset latency was 33 minutes (SD=26.5) where the most commonly reported reason was ‘worry’/ ‘racing thoughts’, average rise time was 9.20 am (SD=1.85) and average hours of actual sleep was 7.53 (SD=1.38) (7.4% reported ≤ 5 hours, 9.3% reported 5-6 hours, 29.6% reported 6-7hours, 25.9% reported between 7-8 hours). Levels of trait anxiety, attentional control, and current sleepiness fell within the normal range (e.g. Alapin et al., 2000; Derryberry and Reed, 2001; Taylor et al., 2005). Participant gender did not interact with findings reported below, nor did the extent to which participants considered themselves to be predominantly morning or evening types (as measured by the Morningness-Eveningness Questionnaire (Horne & Östberg, 1976). 3.1 Associations between sleep quality, trait anxiety, attention control and sleepiness. Subjective poor sleep (PSQI) and insomnia severity (ISI) were strongly associated with increased trait anxiety, reduced attention control and increased sleepiness. Associations with poor sleep were driven by notable effects of sleep quality (PSQI), sleep disturbance (PSQI) and daytime symptoms (PSQI and ISI). Descriptive statistics for all self-report measures are presented in Table 1. As expected following the worry period (compared to pre-worry) participants were less able to focus on their breathing [premean = 8.72 (SD = 1.75), post-mean = 8.38 (SD = 2.15), t (108)=2.61, p<0.05], more likely to experience negative thought intrusions [pre-mean = 0.90, (SD = 1.1), post-mean = 1.58 (SD = 1.44), t (108) = 4.90, p<0.001], and less likely to experience positive thought intrusions [pre-mean = 1.25 (SD = 1.23), postmean = 0.83 (SD = 1.08), t (108)=3.49, p<0.01]. Likewise the worry period increased subjective feelings of worry (pre-worry= 20.33, post-worry = 42.67), t (106)= 7.79, p<0.001) and anxiety (pre-anxiety = 17.04, post-anxiety = 35.39, t (106)= 8.18 , p<0.001). We observed typically high levels of agreement between participant subjective ratings and experimenter ratings of thought valence [0.85 < r’s < 0.92]. The primary analysis of subjective valence ratings below is comparable with an equivalent analysis of experimenter valence ratings. 3.2 Associations between sleep quality, anxiety, attention control and thought intrusions at baseline During the pre-worry period the frequency of thought intrusions (across valence) was positively associated with nocturnal symptoms (ISI), sleep disturbance (PSQI) and daytime sleepiness due to poor sleep (PSQI). Trait anxiety was not significantly correlated with overall thought intrusions during the preworry period.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Frequency of negative thought intrusions was positively associated with subjective insomnia symptom severity (ISI_total) and poor sleep quality (PSQI_total), and also associated with trait anxiety and current sleepiness. Follow-up partial correlations confirmed that poor sleep was significantly associated with negative thought intrusions beyond the effect of current sleepiness (ISI: r =0.21, p=0.03, PSQI: r =0.23, p=0.02) and trait anxiety (ISI: r =0.20, p=0.04, PSQI: r =0.23, p=0.02). Supplementary regression analysis investigated whether specific sleep symptoms (quality, disturbance, daytime dysfunction) accounted for the observed associations between overall poor sleep and negative thought intrusions, however, there were no significant individual predictors within the model (F (3, 103)=3.64, p=0.02). Self-report attentional control was unrelated to the ability to focus on breathing. Self-report measures were unrelated to positive and neutral thought intrusions in this period. 3.3. Associations between sleep quality, anxiety, attention control and thought intrusions following worry. Following the five-minute worry period the frequency of thought intrusions remained positively associated with poor sleep quality (disturbance) and daytime sleepiness due to poor sleep, and in addition was further associated with insomnia severity and trait anxiety. Partial correlations confirmed that insomnia severity was not associated with greater thought intrusions, beyond the effect of anxiety (ISI: r =-0.11, p=0.27). Contrary to findings in the pre-worry (baseline) period, there were no significant associations between negative thought intrusions and measures of poor sleep. Instead, frequency of negative thought intrusions remained strongly associated with trait anxiety, and further associated with reduced self-report attention control and greater daytime sleepiness. A partial correlation confirmed that trait anxiety was associated with greater negative thought intrusions when controlling for baseline negative thought intrusions (r=0.32, p<0.01).
4. Discussion The role of thought intrusions in insomnia is poorly understood and limited to broad discussions of cognitive hyperactivity and negative cognitive activity in the pre-sleep period. Furthermore these observations have been primarily in those with clinical insomnia and where confounding variables (such as comorbid mood and anxiety disorder) might mask associations between poor sleep and thought intrusions. This is the first study to examine on-line, daytime intrusive thought and insomnia symptoms using the thought intrusions task. We revealed unique, positive associations between insomnia symptoms (over the past month) and negative thought intrusions at baseline (prior to explicitly activating worry). Night-time and daytime aspects of poor sleep contributed equally to this relationship, suggesting that negative thought intrusions are related to both sleep disturbance and its daytime consequences in this *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
population, beyond the current level of reported sleepiness. Consistent with previous findings (Hirsch et al., 2009), the worry period increased feelings of anxiety and worry, increased negative thought intrusions and reduced breathing focus. Trait anxiety and self-report attention control (but not sleep measures) were strongly associated with negative thought intrusions following the period of active worry. Why might sleep quality be associated with increased negative thought intrusions in the pre (but not post) worry period, whereas anxiety is more strongly associated with negative intrusions after a period of worry? It is likely that the worry period activated concerns that were particularly salient for those with elevated trait anxiety, and which remained primed for re-activation during the post-worry breathing focus period (consistent with classification systems that emphasise persistent worry as a core symptom of generalized anxiety disorder e.g. DSM-V, 2013). Conversely disturbed sleep was associated with the spontaneous activation of negative thoughts (in the pre-worry period), with broader difficulties focussing attention (post-worry) driven by co-occurring generalized anxiety. We also revealed significant negative associations between both night-time and daytime aspects of insomnia and the ability to focus and maintain attention on breathing at baseline (however, these associations were only observed for disturbance and daytime sleepiness components of the PSQI and night-time symptoms of the ISI). Surprisingly, we did not find an association with trait anxiety. Following the worry period, associations between insomnia severity and breathing focus were strengthened, as too were associations with trait anxiety. These results highlight the high level of shared variance between anxiety, poor sleep, and broader deficits in attention control. This is consistent with evidence that anxiety is associated with poor sleep in clinical samples, and that beyond worry, ruminative thinking (not measured here) might be an important additional feature of sleep disturbance (Carney, Harris, Moss and Edinger, 2010). Interestingly, we did not find associations between self-reported attentional control and breathing focus/negative thought intrusions at baseline, although these were revealed in the post-worry breathing period. The ACS asks individuals to report on their ability to control attention in situations where it may be challenged, e.g. “When I am working hard on something I still get distracted by events around me”. Thus associations between self-report ACS and behavioural measures of attention control (e.g. thought intrusions) might occur only during conditions of high cognitive load/distractibility e.g. following a period of active worry. The results of this study are important for several reasons. Using a novel experimental task we observed that more frequent thought intrusions (particularly negative intrusions) were associated with insomnia symptoms in young adults who commonly experience alterations to sleep environment, shifts to the timing of sleep onset and acute stress (Roth and Roehers, 2003). Due to environmental and biopsychosocial factors such as ineffective coping with sleep disturbance (Yang, Wu, Hseih, Liu and Lu, *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
2003) and increased exposure to sleep interfering events, this population is ‘at risk’ for development of persistent insomnia. Spontaneous intrusive thought, therefore, may be an important aspect of daytime dysfunction which is uniquely associated with insomnia symptoms and may result in a reduced ability to complete daytime tasks efficiently and exacerbate existing mood and anxiety problems during stressful periods. Results are consistent with findings from acute sleep deprivation studies that reveal dysfunction in key emotion neural networks implicated in emotion activation (e.g. amygdala) and regulation (e.g. prefrontal-cortex) following sleep loss (Tempesta et al., 2010; Yoo et al., 2007). They are also consistent with aetiological models of insomnia which consider heightened cognitive arousal as important within insomnia development. Finally, results show that in a ‘poor-sleeping’ population, daytime intrusive thoughts are not characterised by sleep-related concerns, as is commonly observed in clinical populations, but rather by broader concerns that relate to a range of current stressors. There are several limitations to this study. Firstly, the findings relate to intrusive thought in an undergraduate population that has unique sleep characteristics - students may be more able than other sleep-disturbed groups to compensate for sleep loss during the daytime (through napping, delayed rise time). Secondly, the cross-sectional nature of this study means that we cannot infer causation between poor sleep, negative thought intrusions and weakened attentional control. Thirdly, we did not include sleep diaries or an objective measure of sleep (e.g. actigraphy) to corroborate self-assessments of sleep quality. Fourthly, although we have discussed the possibility of negative thought intrusions as a risk factor for an escalating insomnia complaint, the cross-sectional design means that we cannot discriminate between factors which may predispose to poor-sleep, those which may perpetuate poor sleep, and those which arise from an acute poor-sleep episode. Nevertheless, by assessing sleep over the past month in non-treatment seeking individuals, it is likely that we predominantly measured initial acute sleep disturbance. The thought intrusions task provided a sensitive measure of daytime thought intrusions in a poor sleeping population, before and after a period of worry. Thought samples were spontaneous and unique at the level of the individual, overcoming limitations of previous analogue studies which used a standardised stressor to evoke state worry (i.e. speech threat) in order to measure associated cognitive activity. This study is novel and requires replication within other poor-sleeping populations, including those with a clinical sleep disorder. Future studies could extend the use of this task to profile thought intrusions across varying levels of poor sleep/insomnia severity in order to test theories relating to the development of insomnia which emphasise the increasing importance of sleep-related worry (Espie, 2002; Harvey 2002). Furthermore, in line with emerging evidence that attention training towards benign appraisals of threatening stimuli can reduce worry and anxiety in high-worriers (Hirsch et al., 2009), the *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
thought intrusions task may be useful within CBT-I as an outcome tool for measuring change to sleeprelated attentional bias, which is a reliable feature of insomnia disorder (Marchetti et al., 2006). Currently, our understanding of factors involved in the transition from poor sleep to chronic insomnia is limited. Our finding that negatively valenced thought intrusions and poor attentional control are associated with poor sleep/acute insomnia, highlights the potential importance of this mechanism in the development of sleep disorders.
Acknowledgements: Megan Wingfield, Jade Lymn, Louise Kenny and Robin Wickens for their help with data collection. Contributors: LB undertook management of the study, collected and analysed data and led drafting of the paper. MG and DB supported management of the study, analysis and drafting of the paper. Conflict of Interests: LB has no conflict of interests. MG has received support from Eli Lilly to attend scientific conferences and has held research grants from Lundbeck and Pfizer Ltd. On behalf of his employer DSB has held research grants from Bristol-Myers Squibb, Cephalon, Eli Lilly Ltd, GlaxoSmithKline, H. Lundbeck A/S, Pierre Fabre, Pfizer Ltd, Roche and Vernalis Ltd. He has served on advisory boards hosted by Astra-Zeneca, Bristol-Myers Squibb, Eli Lilly Ltd, GlaxoSmithKline, Grunenthal, H. Lundbeck A/S, Pierre Fabre, and Pfizer Ltd. He is a past President of Depression Alliance and a current Medical Patron of Anxiety UK.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
References Alapin, I., Fichten, C. S., Libman, E., Creti, L., Bailes, S., Wright, J., 2000. How is good and poor sleep in older adults and college students related to daytime sleepiness, fatigue, and ability to concentrate? Journal of Psychosomatic Research 49, 381-390. American Academy of Sleep Medicine, 2005. The International Classification of Sleep Disorders: Diagnostic & Coding Manual, 2nd ed. American Academy of Sleep Medicine, Westchester, IL. American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. text revision. American Psychiatric Association, Washington, DC. American Psychiatric Association, 2013. Diagnostic and Statistical Manual of Mental Disorders, 5th ed. American Psychiatric Association, Washington, DC. Barnes, L. L. B., Harp, D, Jung, W. S., 2012. Reliability generalization of scores on the Spielberger StateTrait Anxiety Inventory. Educational and Psychological Measurement 62, 603–618. *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Bastien, C.H., Vallieres, A., Morin, C., 2001. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Medicine 2, 297-306. Borkovec, T. D., Lane, T. W., VanOot, P. H., 1981. Phenomenology of sleep among insomniacs and good sleepers: Wakefulness experience when cortically asleep. Journal of Abnormal Psychology 90, 607- 609. Borkovec, T. D., Robinson, E., Pruzinsky, T., DePree, J. A., 1983. Preliminary exploration of worry: Some characteristics and processes. Behaviour Research Therapy 21, 9–16. Buysse D. J, Reynolds, C.F., Monk, T.H., Berman, S.R., Kupfer, D.J., 1989. The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research. Psychiatry Research 28, 193–213. Carney, C.E., Harris, A.L., Moss, T.G., Edinger, J.D. (2010). Distinguishing rumination from worry in clinical insomnia. Behaviour Research and Therapy 48, 540–546 Dement, W.C., Carskadon, M.A., 1982. An essay on sleepiness. In: Baldy-Moulinier, M. (Ed.) Actualites en Medicine Experimentale: En Homage au Proffeseur P. Passouant. Euromed, Montpellier, France, pp. 47-71. Derryberry, D., Reed, M. A., 2002. Anxiety-related attentional biases and their regulation by attentional control. Journal of Abnormal Psychology 111, 225–236. Ellis, J. G., Gehrman, P., Espie, C., Riemann, D., Perlis, M. L. 2012. Acute insomnia: Current conceptualizations and future directions. Sleep Medicine Reviews 16, 5–14. Espie CA. (2002). Insomnia: conceptual issues in the development, persistence, and treatment of sleep disorders in adults. Annual. Review of Psychology 53, 215–243. Hall, M., Buysse, D. J., Reynolds, C. F., Kupfer, D. J., Baum, A., 1994. Stress-related intrusive thoughts disrupt sleep onset and continuity. Sleep Research 25, 163. Harvey, A. G., 2002. A cognitive model of insomnia. Behaviour. Research and Therapy 40, 869-893. Harvey, A.G., 2005. Unwanted intrusive thought in insomnia. In: Clark, D.A. (Ed.) Intrusive Thought in Clinical Disorders. Guilford Press, New York, pp.30-53. Harvey, A. G., Payne, S., 2002. The management of unwanted pre-sleep thoughts in insomnia: distraction with imagery versus general distraction. Behaviour Research and Therapy 40, 267–277. *Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Harvey, A. G., Tang, N. K. Y., Browning, L. 2005. Cognitive approaches to insomnia. Clinical Psychology Review, 25, 593–611. Hayes, S., Hirsch, C.R., Mathews, A., 2010. Facilitating a benign attentional bias reduces negative thought intrusions. Journal of Abnormal Psychology 119, 235–240. Hirsch, C. R., Hayes, S., Mathews, A., 2009. Looking on the bright side: accessing benign meanings reduces worry. Journal of Abnormal Psychology 118, 44-54. Hoddes, E., Zarcone, V., Smythe, H., Phillips, R., Dement, W.C., 1973. Quantification of sleepiness: a new approach. Psychophysiology 10, 431–437. Horne, J. A., Östberg, 0. (1976). A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology 4, 97-l10. Killingsworth M. A., Gilbert D. T., 2010. A wandering mind is an unhappy mind. Science 330, 932–932. Krebs, G., Hirsch, C.R., Mathews, A., 2010. The effect of attention modification with explicit versus minimal instructions on worry. Behaviour Research and Therapy 48, 251–256. Lund, H. G., Reider, B. D., Whiting, A. B., Prichard, J. R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. Journal of Adolescent Health 46, 124–132. Lundh, L. G., Broman, J. E., 2000. Insomnia as an interaction between sleep-interfering and sleepinterrupting processes. Journal of Psychosomatic Research 49, 299–310. Marchetti, L. M., Biello, S. M., Broomfield, N.M., MacMahon, K.M., Espie C.A., 2006. Who is preoccupied with sleep ? A comparison of attention bias in people with psychophysiological insomnia, delayed sleep phase syndrome and good sleepers using the induced change blindness paradigm. Journal of Sleep Research 15, 212–221. Morin, C., 1993. Insomnia: Psychological Assessment and Management. Guilford Press, New York. Morin, C. M., Belleville, G., Bélanger, L., Ivers, H., 2011. The Insomnia Severity Index: psychometric indicators to detect insomnia cases and evaluate treatment response. Sleep, 34, 601–608. Roth, T., Roehrs, T., 2003. Insomnia: Epidemiology, characteristics, and consequences. Clinical Cornerstone 5, 5-15.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Ruscio, A. M., Borkovec, T. D., 2004. Experience and appraisal of worry among high worriers with and without generalized anxiety disorder. Behaviour Research and Therapy 42, 1469–1482. Spielberger, C.D. Gorusch, R.L., Lushene, R., Vagg, P.R., Jacobs, G.A., 1983. Manual for the State-Trait Anxiety Inventory (Form Y). Consulting Psychologists Press, Palto Alto, CA. Sunnhed, R., Jansson-Fröjmark, M., 2014. Are changes in worry associated with treatment response in cognitive behavioral therapy for insomnia? Cognitive Behaviour Therapy 43, 1-11. Taylor, D. J., Bramoweth, A. D., Grieser, E., Tatum, J. I., Roane, B. M. (2013). Epidemiology of insomnia in college students: relationship with mental health, quality of life, and substance use difficulties. Behavior Therapy 44, 339–348. Taylor, D.J., Lichstein, K.L., Durrence, H.H., Reidel, B.W., Bush, A.J., 2005. Epidemiology of insomnia, depression, and anxiety. Sleep 28, 1457–1464. Tempesta, D., Couyoumdjian, A., Curcio, G., 2010. Lack of sleep affects the evaluation of emotional stimuli. Brain Research Bulletin 82, 104–108. Wells, A., Morrison, A. P., 1994. Qualitative dimensions of normal worry and normal obsessions: A comparative study. Behaviour Research and Therapy 32, 867-870. Yoo, S-S, Gujar, N., Hu, P., Jolesz, F. A., Walker, M. P., 2007. The human emotional brain without sleep — a prefrontal amygdala disconnect. Bipolar Disorders 17, 877-878.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Table 1: Sample characteristics and associations between subjective sleep, anxiety and thought intrusions.
SSS
ACS
STAI
Baseline
Baseline
Post-worry
Post-worry
breathing
negative
breathing
negative
focus
intrusions
focus
intrusions
M
SD
ISI total
8.21
4.50
0.28**
-0.28**
0.47**
-0.18 (.06)
0.25**
-0.21*
0.19 (.05)
Daytime
5.15
3.00
0.28**
-0.32**
0.54**
-0.14
0.20*
-0.18
0.14
Nighttime
3.06
1.98
0.19
-0.15
0.27**
-0.20**
0.27**
-0.20
0.13
PSQI total
6.55
3.18
0.31**
-0.27**
0.47**
-0.16
0.26**
-0.14
0.13
Quality
1.26
0.68
0.28**
-0.24*
0.35**
-0.10
0.27**
-0.02
0.05
Disturbance
1.23
0.47
0.24*
-0.26**
0.45***
-0.22*
0.22*
-0.22*
0.13
Latency
1.58
0.87
0.23*
-0.13
0.19
-0.05
0.14
-0.06
0.17
Duration
0.29
0.63
0.05
-0.01
0.19
-0.17
0.18
-0.15
0.14
Efficiency
0.87
1.03
0.17
-0.13
0.34**
-0.09
0.16
-0.11
0.02
Medication
0.17
0.49
0.31**
-0.02
0.06
-0.05
-0.04
0.06
0.04
Daytime
1.15
0.71
0.31**
-0.42**
0.54***
-0.28**
0.20*
-0.20*
0.19*
SSS
3.03
0.90
-
-0.29**
0.33**
0.08
0.23*
-0.10
0.14
ACS
47.78
8.43
-
-
-0.57***
0.13
-0.12
0.20*
-0.40**
STAI
40.17
10.54
-
-
-
-0.15
0.21*
-0.21*
0.37**
dysfunction
NB: Scores in parentheses are p-values that reflect statistical trends that fall short of the conventional significance threshold p<0.05. ISI; Insomnia Severity Index, PSQI; Pittsburgh Sleep Quality Index; SSS; Stanford Sleepiness Scale, ACS; Attentional Control Scale, STAI; Spielberger Trait Anxiety Inventory, *p<0.05, **p<0.01***, p<0.001.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)
Highlights First study of association between insomnia symptoms and daytime intrusive thoughts. Insomnia symptoms predicted subjective and behavioural measures of thought control. Insomnia symptoms were uniquely associated with negative thought intrusions. We highlight thought control/intrusions as a therapeutic target in early insomnia.
*Corresponding authors: Louise Baker & Matthew Garner: [email protected] (L.D.Baker), [email protected] (M.Garner)