- Email: [email protected]
Sleep disturbances and suicidal ideation in sleep medical center patients
Journal of Affective Disorders 131 (2011) 422–427
Contents lists available at ScienceDirect
Journal of Affective Disorders j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / j a d
Preliminary communication
Sleep disturbances and suicidal ideation in sleep medical center patients Barry Krakow a,b,c,⁎, Jessica D. Ribeiro d, Victor A. Ulibarri a,b, Jessica Krakow a,b, Thomas E. Joiner Jr. d a b c d
Sleep & Human Health Institute, Albuquerque, NM, United States Maimonides Sleep Arts & Sciences Ltd, Albuquerque, NM, United States Los Alamos Medical Center Sleep Laboratory, Los Alamos, NM, United States Florida State University, Tallahassee, FL, United States
a r t i c l e
i n f o
Article history: Received 7 October 2010 Received in revised form 13 November 2010 Accepted 2 December 2010 Available online 6 January 2011 Keywords: Sleep Sleep disturbance Insomnia Suicidal ideation Suicide
a b s t r a c t Objective: The purpose of this investigation was two-fold: first, we examined associations between suicidal ideation, maladaptive sleep patterns and abnormal sleep behaviors in a sleep center population, an understudied population in the domain of suicide research; and then, we explored whether significant associations remained after accounting for the possible influence of depressive symptoms. Method: Data were analyzed from intake information obtained from 1584 adult patients presenting at a community-based private sleep medical center. The sample was parsed into a Suicidal Ideation (SI) group (N = 211) and No Suicidal Ideation (NSI) group (N = 1373). Comparisons of these groups were made on measures of self-reported sleep complaints, habits, and behaviors, suicidal ideation, depressive symptoms, and associated psychopathology. Results: Approximately 13% of participants reported suicidal ideation. Clinically significant suicidal ideation was present in 4.5% of the sample. Compared to the NSI group, the SI group showed a pervasive pattern of significantly greater frequency or severity of sleep problems in areas of insomnia, nightmares and other parasomnia behaviors, poor sleep quality, and sleeprelated psychophysiologic conditioning as well as worse sleep-related impairment and quality of life. Several relationships were significant after controlling for depressive symptoms. Discussion: Suicidal ideation was consistently associated with a broad array of sleep complaints, even when controlling for level of depressive symptoms. As these self-reported sleep disturbances are treatable sleep disorders, future research should examine the efficacy of sleep and behavioral medicine for reducing the risk of suicidal ideation. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Over 30,000 individuals die by suicide each year in the United States alone. For every death by suicide, there are approximately 10 to 25 nonlethal attempts (Maris, 1992). Population surveys of lifetime prevalence indicate approximately 5% of the United States population reports a suicide
⁎ Corresponding author. Sleep & Human Health Institute, 6739 Academy N.E., Suite 380, Albuquerque, NM 87109, United States, Tel.: + 1 505 998 7204; fax: + 1 505 998 7220. E-mail address: [email protected] (B. Krakow). 0165-0327/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2010.12.001
attempt, 4% a plan, and 14% ideation (Kessler et al., 1999). Although suicide is the 11th leading cause of death in the U.S. (Centers for Disease Control and Prevention, 2005), it is largely preventable. Research advancing our knowledge of risk factors for suicide continues to enhance our ability to predict and prevent death by suicide (Borges et al., 2008; Mann et al., 2005). Recent developments have highlighted sleep disturbances as significant risk factors for suicidal ideation and behaviors (Bernert and Joiner, 2007). Severity of global insomnia has been identified as a significant—and, importantly, modifiable—short-term risk factor for suicide (Fawcett et al., 1990; Aĝargün et al., 1997a, 2007). Hypersomnia and poor
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
sleep quality have both been predictive of eventual death by suicide (Aĝargün et al., 1997b; Turvey et al., 2002). Suicidal individuals evidence significantly higher rates of nightmares, especially when suffering from depression (Ağargün et al., 1998, 2007; Tanskanen et al., 2001). Other sleep disturbances have also been implicated as potential suicide risk factors, including lower sleep efficiency, longer sleep latency, and sleep-disordered breathing (Sabo et al., 1991; Ağargün and Cartwright, 2003; Krakow et al., 2000). The failure to account for the effects of depression on sleep and suicide is a limitation in this literature. Although studies of depressed patient samples have provided evidence for a clear relationship between sleep and suicide, it remains unclear whether these findings would persist after controlling for depression. Although few studies have addressed this issue, there is some evidence supporting the relationship between suicidality and sleep problems, beyond the effect of depressive symptom severity (Keshavan et al., 1994; Smith et al., 2004; Bernert and Joiner, 2007) or chronicity of depressive symptoms (Chellappa and Araújo, 2007). Another limitation is that individuals suffering from sleep problems symptomatic of psychiatric distress rarely seek formal mental health treatment (Wojnar et al., 2009). For instance, less than 4% of individuals who suffer from insomnia report receiving any psychiatric services within the past 6 months (Weissman et al., 1997). Therefore, relying solely on the mental health field to detect individuals at risk may limit opportunities to effectively assess or intervene in other clinic populations. By extending suicide detection and early intervention efforts to other service providers, prevention efforts could be enhanced. One viable area of intervention would be outpatient sleep centers, which are equipped to treat individuals suffering from sleep disturbances that might impact suicidality (e.g., Krahn et al., 2008). To our knowledge, no studies have examined the association between sleep and suicide in large patient samples presenting at sleep clinics. Therefore, the first aim of the study was to explore the associations between a range of self-reported sleep problems and suicidal ideation in a sleep medical center population. Secondly, we examined whether associations remained after accounting for the possible influence of depressive symptoms. In light of past research, we anticipated that a broad array of sleep complaints and related symptoms would be associated with suicidal ideation and that several of these relationships would remain after controlling for severity of depressive symptoms.
2. Methods 2.1. Participants and procedure This study was a retrospective chart review reviewed and approved by the Los Alamos Medical Center IRB. Data were collected between January 2005 and June 2009. Patients were administered two waves of self-report measures: at intake and then between one and four weeks afterward. As only 55% of the sample completed both waves, we restricted the sample to include individuals who had data for both time points, yielding a convenience sample of 1584 participants. Refer to Table 1 for demographic data.
423
2.2. Measures 2.2.1. Sleep Medicine History (SMH; Krakow et al., 2001a,b) The SMH is a comprehensive self-report questionnaire that assesses a range of sleep-related concerns based on American Academy of Sleep Medicine (AASM) nosology. Information is collected on sleep indices, insomnia, sleep quality, sleep fragmentation factors, sleep-related daytime impairment, sleep-disordered breathing, restless legs syndrome, and periodic limb movement disorder. 2.2.2. Insomnia Severity Index (ISI; Bastien et al., 2001) The ISI is a seven-item self-report scale that assesses subjective symptoms of insomnia, including the degree of distress associated with each symptom. 2.2.3. Disturbing Dream and Nightmare Severity Index (DDNSI; Krakow, 2006) The DDNSI is a five-item self-report inventory designed to assess the frequency, severity, and intensity of nightmares. 2.2.4. Functional Outcomes Sleep Questionnaire (FOSQ ; Weaver et al., 1997) The FOSQ is a 30-item self-report measure designed to assess the effects of excessive daytime sleepiness on daily functioning. The FOSQ contains five subscales: general productivity, social outcome, activity level, intimacy/sexual functioning, and vigilance. 2.2.5. Quality of Life Enjoyment and Satisfaction QuestionnaireShort Form (Q-LES-Q ; Endicott et al., 1993) The Q-LES-Q is a self-report inventory designed to assess enjoyment and satisfaction in various areas of daily living. 2.2.6. Time Monitoring Behavior (TMB-10) The TMB-10 is a newly-constructed scale designed as a measure of time monitoring behavior and associated frustration. The ten-item scale is comprised of two subscales: the first, assessing time monitoring behavior related to sleep onset and the second, assessing behaviors associated with awakenings after sleep onset. Coefficient alpha in this sample was 0.95, indicating strong internal consistency. 2.2.7. Depressive Symptoms Inventory-Suicide Subscale (DSI-SS; Metalsky and Joiner, 1997) The DSI-SS consists of four self-report items focusing on frequency and intensity of suicidal thoughts and impulses during the past 2 weeks. 2.2.8. Hopkins Symptom Checklist (HSCL-25; Hesbacher, 2001) The HSCL-25 is designed as a screening assessment for anxiety and depression consisting of two subscales designed to measure these symptoms. 2.2.9. Psychiatric history As part of the intake procedures, individuals were asked to complete questionnaires that included questions about past psychiatric conditions, use of psychiatric medications, and psychotherapy experience.
424
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
Table 1 Sociodemographics & psychiatric history a. Characteristic
SI (n = 211)*
NSI (n = 1373)*
p, d, and differences of proportion values b
Age, years Gender Male Female Body mass index, Kg/m2 Marital status Married, living w/partner Single, divorced, or other Education Bachelors degree or higher Some college or lower Ethnicity Hispanic Caucasian Other Anxiety disorder Yes No Depression Yes No PTSD Yes No Trauma exposure Yes No
48.64 ± 11.85
49.93 ± 13.32
p = 0.18; d = 0.10
99 (46.9) 112 (53.1) 31.23 ± 8.96
766 (55.8) 607 (44.2) 30.78 ± 7.54
p = 0.01; 9% p = 0.43; d = 0.05
131 (62.4) 79 (37.6)
945 (69.0) 424 (31.0)
p = 0.03; 7%
118 (58.4) 84 (41.6)
757 (56.4) 585 (43.6)
p = 0.32; 2%
25 (11.9) 155 (73.9) 30 (14.3)
313 (22.8) 925 (67.4) 135 (9.8)
p = 0.001; 5%
93 (44.1) 118 (55.9)
264 (19.2) 1109 (80.8)
p = 0.001; 25%
148 (70.1) 63 (29.9)
463 (33.7) 910 (66.3)
p = 0.001; 37%
48 (22.7) 163 (77.3)
86 (6.3) 1287 (93.7)
p = 0.001; 16%
119 (56.7) 91 (43.3)
393 (28.8) 973 (71.2)
p = 0.001; 28%
Note. SI = Suicidal Ideation group; NSI = Non-suicidal Ideation group. a Dichotomous variables expressed as n(% of total) and continuous variables expressed as mean ± SD. b p value determined using χ2 analysis for dichotomous variables and One-Way ANOVA for continuous variables. Differences of Proportion are reported for dichotomous variables. Cohen's reported for continuous variables.
2.3. Data analysis The sample was first parsed into two groups based on DSISS total scores: individuals who presented endorsing suicidal ideation (i.e. DSI ≥ 1) were placed into the Suicidal Ideation (SI) group (n = 211). Patients who did not present with suicidal ideation (i.e. DSI-SS total score = 0) were placed in the No Suicidal Ideation (NSI) group (n = 1373). One-way ANOVA contrasted means between groups and Cohen's d was calculated for each comparison. Chi-square analyses were conducted on dichotomous variables and proportional differences between groups were calculated as effect sizes. Given that both sleep disturbances and suicidality are commonly associated with depression, we also explored the effects of suicidal ideation on sleep disturbance over and above the effects of depression. Using analysis of covariance (ANCOVA), we examined the differences in sleep disturbances between groups with level of depressive symptoms as measured by the HSCL-25 as a covariate. For these analyses, statistical significance was established at p ≤ 0.01 for all analyses. 3. Results Approximately 13.3% of participants reported suicidal ideation. Over one-third of those individuals reported clinically significant levels of suicidal ideation (i.e. 4.5% of the sample). Sleep problems were consistently associated with suicidality. Compared to the NSI group, the SI group
evidenced pervasive symptoms in a number of sleep-related domains (Table 2). On average, sleep problems were substantially more chronic in the SI group (F(1, 1501) = 29.34, p b 0.001); the SI group reported suffering from sleep problems for approximately 15 years (M = 15.24; SD = 13.08) and the NSI group reported suffering from sleep problems for just over a decade (M = 10.81 years; SD = 11.02). Insomnia symptoms were more severe in the SI group compared to the NSI group (F(1, 1582) = 75.16, p b 0.001). The SI group reported more awakenings per night (F(1, 1571) = 9.263, p b 0.01) and greater difficulty falling back to sleep (F(1, 1515) = 12.81, p b 0.001). Nightmares were more severe in the SI group (F(1, 1582) = 18.10, p b 0.001). Several areas of more severe sleep symptoms were present in the SI group compared to the NSI group for parasomnia behaviors, including “acting out dreams” (F(1, 1546) = 5.80, p = 0.01) and making disruptive noises during sleep (F(1, 1562) = 13.31, p b 0.001) as well as psychophysiological conditioning, including time monitoring behavior (F(1, 1583) = 50.98, p b 0.001), losing sleep over losing sleep (F(1, 1542) = 13.31, p b 0.001), and failing to create a positive sleep environment (F(1, 1251) = 10.03), p b 0.01). Not surprisingly, the SI group reported poorer subjective sleep quality as compared to the NSI group (F(1, 1582)= 21.79, p b 0.001). The SI group evidenced longer sleep onset latencies (F(1, 1549) = 7.551, p b 0.01) and longer time in bed (F(1, 1576) = 19.49, p b 0.01). Their sleep efficiency (percent of time asleep in bed), was also significantly worse than the NSI group
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
425
Table 2 Sleep disturbances associated with suicidal ideation. Characteristic
SI (n = 211)*
NSI (n = 1373)*
p, d, and Differences of Proportion values a
Insomnia symptoms Insomnia Severity Index (ISI) b, total score Total awakenings per night Trouble returning to sleep Yes No Subjective sleep indices Sleep onset latency, min. Total time in bed, h Wake after sleep onset, min. Sleep efficiency, % Sleep quality Subjective sleep c Quality Depth Visual analog scale d Sleepiness Tiredness Nightmare history Bad dreams or nightmares disrupt sleep Yes No DDNSI, total score Parasomnia symptomotology & psychophysiologic conditioning Acting out dreams/REM behavior disorder Yes No Disruptive noises/screaming during sleep Yes No Psychophysiologic conditioning TBM-10, total score Lose sleep over losing sleep Yes No Created a positive sleep environment Yes No Daily functioning & quality of life FOSQ , total score Q-LES-Q , total score
18.48 ± 5.70 3.62 ± 2.85
14.61 ± 6.08 3.15 ± 2.35
p = 0.001; d = 0.66 p = 0.01; d = 0.18
132 (63.2) 77 (36.8)
708 (51.9) 656 (48.1)
p = 0.001; 12%
75.46 ± 132.00 8.22 ± 2.13 109.14 ± 139.08 74.04 ± 23.29
45.59 ± 146.90 7.72 ± 1.43 74.87 ± 124.11 82.64 ± 24.80
p = 0.01; d = 0.21 p = 0.001; d = 0.28 p = 0.001; d = 0.13 p = 0.001; d = 0.36
4.89 ± 1.47 3.02 ± 1.37
4.38 ± 1.49 2.72 ± 1.24
p = 0.001; d = 0.34 p = 0.001; d = 0.23
6.55 ± 2.20 7.54 ± 2.08
5.79 ± 2.48 6.54 ± 2.39
p = 0.001; d = 0.32 p = 0.001; d = 0.45
73 (34.6) 138 (65.4) 7.12 ± 8.26
248 (18.1) 1120 (81.9) 3.32 ± 6.06
p = 0.001; 17% p = 0.001; d = 0.52
64 (31.1) 142 (68.9)
313 (23.3) 1028 (76.7)
p = 0.01; 8%
87 (42.2) 119 (57.8)
396 (29.6) 941 (70.4)
p = 0.001; 13%
16.89 ± 8.37
12.61 ± 8.08
p = 0.001; d = 0.52
94 (57.3) 70 (42.7)
333 (31.5) 724 (68.5)
p = 0.001; 26%
97 (56.7) 74 (43.3)
745 (68.9) 336 (31.1)
p = 0.001; 12%
12.62 + 3.56 47.80 + 10.71
15.36 ± 3.27 56.84 + 10.09
p = 0.001; d = 0.80 p = 0.001; d = 0.86
Note. SI = Suicidal Ideation group; NSI = Non-suicidal Ideation group. * Dichotomous variables expressed as n (% of total) and continuous variables expressed as mean ± SD. a p value determined using χ2 analysis for dichotomous variables and One-Way ANOVA for continuous variables. b ISI — Each question scored on scale of 0 to 4 based on increasing severity of the symptom, with total score ranges from 0 to 28. c Lower scores indicate a better response. d VAS Scales (sleepy and tired) — scored on a 0 to 10 metric with scores ≥7 indicative of severe symptoms.
(F(1, 1574)= 21.96, p b 0.001). Moreover, the SI group endorsed significantly lighter sleep (F(1, 1582) = 10.63, p = 0.001). The SI group also reported feeling sleepier (F(1, 1581) = 18.10, p b 0.001) and more fatigued (F(1, 1580)= 32.77, p b 0.001) during the day. The SI group also reported that their excessive sleepiness during the day had a greater impact on their daytime functioning (F(1, 1542) = 119.86, p b 0.001, d = 0.80). Relatedly, the SI group also reported poorer overall quality of life as compared to the non-SI group (F(1, 1573) = 144.31, p b 0.001, d = 0.86). In addition to sleep difficulties, the SI group also endorsed significantly greater psychopathology, including depression (F(1, 1582) = 109.32, p b 0.001). The SI group had a mean score of 1.4 (SD = 0.62) on the depression scale of the HSCL whereas the mean score for the NSI group was 0.66 (SD = 0.49). When controlling for the effects of depression,
the SI group evidenced more chronic sleep difficulties compared to the NSI group (F(1,1582) = 10.44, p b 0.001). Furthermore, the relationship between the presence of suicidal ideation and sleep quality also remained significant over and above the effects of depression, (F(1,1582) = 9.58, p b 0.05) such that the SI group also endorsed significantly poorer quality of sleep compared to the NSI group. Lastly, the SI group continued to evidence significantly higher levels of daily fatigue than the NSI group (F(1,1582) = 5.305, p = 0.021), over and above the effects of depression. Analyses also revealed several non-significant trends. Controlling for depression, analyses indicated that the SI group continued to have lighter sleep (F(1,1582) = 3.28, p = 0.07) as compared to the NSI group. Above and beyond the effects of depression, the SI group spent a longer time in bed (F(1, 1582) = 3.57, p = 0.06) than the NSI group.
426
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
Analyses also indicated that the frequency of disturbing dreams and nightmares was greater in the SI group compared to the NSI group (F(1,1582) = 3.30, p = 0.07). 4. Discussion Suicidal ideation was endorsed by 13.3% of the present sample of sleep center patients. As expected, sleep disturbances were consistently associated with the presence of suicidal ideation. Suicidal individuals evidenced greater frequency and severity of various sleep problems as compared to non-suicidal individuals. By exploring effects of sleep on suicidal ideation when controlling for depression severity, our findings serve to replicate and extend the evidence for the unique contribution of sleep disturbances on suicide risk. Several sleep variables were significantly associated with suicidal ideation beyond the effects of depression. In particular, chronicity of sleep problems, daytime fatigue, and poor sleep quality are independently associated with suicidal ideation. These relationships fall in line with those of prior research (e.g., Wojnar et al., 2009; Aĝargün et al., 1997a,b; Turvey et al., 2002; Chellappa and Araújo, 2006). Certain sleep-focused interventions may be pertinent to treat sleep-disordered individuals experiencing suicidal ideation. Educating patients on basic sleep hygiene may improve quality of sleep. Stimulus control therapy, which focuses on reducing conditioned arousal associated with bedtime cues, as well as sleep restriction therapy are effective treatments for insomnia and may enhance sleep efficiency (Morin, 1993). Imagery rehearsal therapy is an effective treatment in reducing nightmares and disturbing dreams as well as decreasing insomnia symptoms (Krakow et al., 2001a,b). Together or separately, these sleep-focused interventions improve sleep quality problems, a key association observed in this study, and they are readily testable on populations reporting suicidal ideation. Examining the potential utility of these interventions in reducing suicidal ideation in sleep-disordered patients would be an important area for future research. Several limitations of are worth highlighting. First, the cross-sectional nature of the study precludes strong causal inferences. Future longitudinal studies designed to establish temporal precedence of the variables would be useful. Secondly, results may not generalize outside sleep center settings. In addition, the study is limited in that formal psychiatric diagnoses were not established. Given the reliability and validity of the HSCL-25, however, we would expect similar findings in patients formally diagnosed with MDD. Also, as a newly developed measure, the psychometric properties of the TMB-10 have not been well-established and further research is warranted on its reliability and validity. Lastly, definitive statements regarding the association between sleep variables and suicidal behavior cannot be made based on the current findings, given that the present study focused on suicidal ideation. Further research examining the relationships between sleep variables and suicidal behavior is crucial. Bearing in mind its limitations, the present study's findings have a number of clinical implications. First, collecting information about sleep would likely enhance suicide risk assessments. Furthermore, clinicians should be aware of the possibility that sleep disturbances may signal increased risk of suicidal ideation. Assessing the chronicity of sleep problems,
sleep quality, and daily fatigue would be most informative beyond assessing for depressive symptoms. Findings from the current investigation suggest that treating sleep difficulties may be a possible means of reducing associated risk of suicidal ideation; however, future research is necessary to evaluate this proposition. Disturbed sleep is a particularly promising area for intervention because it is easily modifiable through the use of medication or behavioral interventions. Evaluating the efficacy of sleep-focused interventions (e.g., sleep hygiene, stimulus control, and imagery rehearsal therapy) as a means of reducing risk of suicidal ideation would likely prove to be a promising line of future research. Role of funding source The present study did not have a funding source. Conflicts of interest Dr. Barry Krakow reported the following conflicts of interest: • 5 sites that provide education and offer products and services for sleep disorders patients: www.nightmaretreatment.com www.sleeptreatment.com www.sleepdynamictherapy.com www.soundsleepsoundmind.com www.nocturiacures.com www.ptsdsleepclinic.com • 3 books marketed and sold for sleep disorders patients: Insomnia Cures Turning Nightmares into Dreams Sound Sleep, Sound Mind • Ownership of one commercial sleep center: Maimonides Sleep Arts & Sciences, Ltd • Presidency of a non-profit sleep research center, the Sleep & Human Health Institute (www.shhi.org) that occasionally provides consultation services or receives grants for pilot studies, the most recent of which were: ∘ ConAlma. $5000 February, 2009 (sleep and obesity screening and education) ∘ Respironics, Inc $50,000 January, 2009 (study on prevalence of SDB in insomnia patients) ∘ GlaxoSmithKline $2500 July, 2008 (consulting on research on Breathe Right nasal strips) ∘ Covidien, Inc. $2500, August 2008 (consulting on PAP therapy devices) All other authors denied any possible conflict of interest with other people or organizations within 3 years of beginning the submitted work that could inappropriately influence the present research study.
Acknowledgements The authors have no acknowledgements. References Ağargün, M.Y., Cartwright, R., 2003. REM sleep, dream variables and suicidality in depressed patients. Psychiatry Res. 119 (1–2), 33–39. Aĝargün, M.Y., Kara, H., Solmaz, M., 1997a. Sleep disturbances and suicidal behavior in patients with major depression. J. Clin. Psychiatry 58 (6), 249–251. Aĝargün, M.Y., Kara, H., Solmaz, M., 1997b. Subjective sleep quality and suicidality in patients with major depression. J. Psychiatr. Res. 31 (3), 377–381. Ağargün, M.Y., Çilli, A.S., Kara, H., Tarhan, N., Kincir, F., Öz, K., 1998. Repetitive and frightening dreams and suicidal behavior in patients with major depression. Compr. Psychiatry 39 (4), 198–202. Ağargün, M.Y., Besiroglu, L., Cilli, A.S., Gulec, M., Aydin, A., Inci, R., Selvi, Y., 2007. Nightmares, suicide attempts, and melancholic features in patients with unipolar major depression. J. Affect. Disord. 98 (3), 267–270.
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427 Bastien, C.H., Vallieres, A., Morin, C.M., 2001. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Med. 2 (4), 297–307. Bernert, R.A., Joiner, T.E., 2007. Sleep disturbances and suicide risk: a review of the literature. Neuropsychiatr. Dis. Treat. 3 (6), 735–743. Borges, G., Angst, J., Nock, M., Ruscio, A., Kessler, R., 2008. Risk factors for the incidence and persistence of suicide-related outcomes: a 10-year followup study using the National Comorbidity Surveys. J. Affect. Disord. 10, 25–33. Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Web-based Injury Statistics Query and Reporting System (WISQARS). Retrieved from: www.cdc.gov/ncipc/wisqars. Chellappa, S.L., Araújo, J.F., 2006. Excessive daytime sleepiness in patients with depressive disorder. Rev. Bras. Psiquiatr. 28 (2), 1–7. Chellappa, S.L., Araújo, J.F., 2007. Sleep disorders and suicidal ideation in patients with depressive disorder. Psychiatry Res. 153 (2), 131–136. Endicott, J., Knee, J., Harrison, W., Blumenthal, R., 1993. Quality of Life Enjoyment and Satisfaction Questionnaire: a new measure. Psychopharmacol. Bull. 29, 321–326. Fawcett, J., Scheftner, W.A., Fogg, L., Clark, D.C., 1990. Time-related predictors of suicide in major affective disorder. Am. J. Psychiatry 147 (9), 1189–1194. Hesbacher, P.T., 2001. Psychiatric illness in family practice. J. Clin. Psychiatry 41 (1), 6–10. Keshavan, M.S., Reynolds, C.F., Montrose, D., Miewald, J., Downs, C., Sabo, E.J., 1994. Sleep and suicidality in psychotic patients. Acta Psychiatr. Scand. 89, 122–125. Kessler, R.C., Borges, G., Walters, E.E., 1999. Prevalence of and risk factors for lifetime suicide attempts in the national comorbidity survey. Arch. Gen. Psychiatry 56 (7), 617–626. Krahn, L.E., Miller, B.W., Bergstrom, L.R., 2008. Rapid resolution of intense suicidal ideation after treatment of severe obstructive sleep apnea. J. Clin. Sleep Med. 4 (1), 64–65. Krakow, B., 2006. Nightmare complaints in treatment-seeking patients in clinical sleep medicine settings: diagnostic and treatment implications. Sleep 29 (10), 1313–1319. Krakow, B., Artar, A., Warner, T.D., Melendrez, D., Johnston, L., Hollifield, M., Koss, M., 2000. Sleep disorder, depression and suicidality in female sexual assault survivors. Crisis J. Crisis Interv. Suicide Prev. 21 (4), 163– 170.
427
Krakow, B., Holliefield, M., Johnston, L., Koss, M., Schrader, R., Warner, T., Prince, H., 2001a. Imagery Rehearsal Therapy for chronic nightmares in sexual assault survivors with posttraumatic stress disorder. JAMA 286, 537–545. Krakow, B., Melendrez, D., Ferreira, E., Clark, J., Warner, T.D., Sisley, B., Sklar, D., 2001b. Prevalence of insomnia symptoms in patients with sleep-disordered breathing. Chest 120, 1923–1929. Mann, J.J., Apter, A., Bertolote, J., Beautrais, A., Currier, D., Haas, A., Hendin, H., 2005. Suicide prevention strategies: a systematic review. J. Am. Med. Assoc. 294, 2064–2074. Maris, R.M., 1992. Assessment and Prediction of Suicide. In: Maris, R.A., Berman, A.L., Maltsberger, J.T. (Eds.), Guilford Press, New York. Metalsky, G.I., Joiner Jr., T.E., 1997. The hopelessness depression symptom questionnaire. Cogn. Ther. Res. Spec. Issue Cogn. Pers. Subtypes Depress. 21 (3), 359–384. Morin, C.M., 1993. Insomnia: Psychological Assessment and Management. Guilford Press, New York. Sabo, E., Reynolds, C.F., Kupfer, D.J., Berman, S.R., 1991. Sleep, depression, and suicide. Psychiatry Res. 36 (3), 265–277. Smith, M.T., Perils, M.L., Haythornthwaite, J.A., 2004. Suicidal ideation in outpatients with chronic musculoskeletal pain: an exploratory study of the role of sleep onset insomnia and pain intensity. Clin. J. Pain 20 (2), 111–118. Tanskanen, A., Tuomilehto, J., Viinamäki, H., Vartiainen, E., Lehtonen, J., Puska, P., 2001. Nightmares as predictors of suicide. Sleep J. Sleep Sleep Disord. Res. 24 (7), 844–847. Turvey, C.L., Conwell, Y., Jones, M.P., Phillips, C., Simonsick, E., Pearson, J.L., Wallace, R., 2002. Risk factors for late-life suicide: a prospective community-based study. Am. J. Geriatr. Psychiatry Spec. Issue Suicidal Behaviors Older Adults 10 (4), 398–406. Weaver, T.E., Laizner, A., Evans, L.K., Maislin, G., Chugh, D.K., Lyons, K., Dinges, D.F., 1997. An instrument to measure functional status outcomes for disorders of excessive sleepiness. Sleep 20, 835–843. Weissman, M.M., Greenwald, S., Nino-Murcia, G., Dement, W.C., 1997. The morbidity of insomnia uncomplicated by psychiatric disorders. Gen. Hosp. Psyhiatry 19 (4), 245–250. Wojnar, M., Ilgen, M.A., Wojnar, J., McCammon, R.J., Valenstein, M., Brower, K.J., 2009. Sleep problems and suicidality in the national comorbidity survey replication. J. Psychiatr. Res. 43 (5), 526–531.
Contents lists available at ScienceDirect
Journal of Affective Disorders j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / j a d
Preliminary communication
Sleep disturbances and suicidal ideation in sleep medical center patients Barry Krakow a,b,c,⁎, Jessica D. Ribeiro d, Victor A. Ulibarri a,b, Jessica Krakow a,b, Thomas E. Joiner Jr. d a b c d
Sleep & Human Health Institute, Albuquerque, NM, United States Maimonides Sleep Arts & Sciences Ltd, Albuquerque, NM, United States Los Alamos Medical Center Sleep Laboratory, Los Alamos, NM, United States Florida State University, Tallahassee, FL, United States
a r t i c l e
i n f o
Article history: Received 7 October 2010 Received in revised form 13 November 2010 Accepted 2 December 2010 Available online 6 January 2011 Keywords: Sleep Sleep disturbance Insomnia Suicidal ideation Suicide
a b s t r a c t Objective: The purpose of this investigation was two-fold: first, we examined associations between suicidal ideation, maladaptive sleep patterns and abnormal sleep behaviors in a sleep center population, an understudied population in the domain of suicide research; and then, we explored whether significant associations remained after accounting for the possible influence of depressive symptoms. Method: Data were analyzed from intake information obtained from 1584 adult patients presenting at a community-based private sleep medical center. The sample was parsed into a Suicidal Ideation (SI) group (N = 211) and No Suicidal Ideation (NSI) group (N = 1373). Comparisons of these groups were made on measures of self-reported sleep complaints, habits, and behaviors, suicidal ideation, depressive symptoms, and associated psychopathology. Results: Approximately 13% of participants reported suicidal ideation. Clinically significant suicidal ideation was present in 4.5% of the sample. Compared to the NSI group, the SI group showed a pervasive pattern of significantly greater frequency or severity of sleep problems in areas of insomnia, nightmares and other parasomnia behaviors, poor sleep quality, and sleeprelated psychophysiologic conditioning as well as worse sleep-related impairment and quality of life. Several relationships were significant after controlling for depressive symptoms. Discussion: Suicidal ideation was consistently associated with a broad array of sleep complaints, even when controlling for level of depressive symptoms. As these self-reported sleep disturbances are treatable sleep disorders, future research should examine the efficacy of sleep and behavioral medicine for reducing the risk of suicidal ideation. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Over 30,000 individuals die by suicide each year in the United States alone. For every death by suicide, there are approximately 10 to 25 nonlethal attempts (Maris, 1992). Population surveys of lifetime prevalence indicate approximately 5% of the United States population reports a suicide
⁎ Corresponding author. Sleep & Human Health Institute, 6739 Academy N.E., Suite 380, Albuquerque, NM 87109, United States, Tel.: + 1 505 998 7204; fax: + 1 505 998 7220. E-mail address: [email protected] (B. Krakow). 0165-0327/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2010.12.001
attempt, 4% a plan, and 14% ideation (Kessler et al., 1999). Although suicide is the 11th leading cause of death in the U.S. (Centers for Disease Control and Prevention, 2005), it is largely preventable. Research advancing our knowledge of risk factors for suicide continues to enhance our ability to predict and prevent death by suicide (Borges et al., 2008; Mann et al., 2005). Recent developments have highlighted sleep disturbances as significant risk factors for suicidal ideation and behaviors (Bernert and Joiner, 2007). Severity of global insomnia has been identified as a significant—and, importantly, modifiable—short-term risk factor for suicide (Fawcett et al., 1990; Aĝargün et al., 1997a, 2007). Hypersomnia and poor
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
sleep quality have both been predictive of eventual death by suicide (Aĝargün et al., 1997b; Turvey et al., 2002). Suicidal individuals evidence significantly higher rates of nightmares, especially when suffering from depression (Ağargün et al., 1998, 2007; Tanskanen et al., 2001). Other sleep disturbances have also been implicated as potential suicide risk factors, including lower sleep efficiency, longer sleep latency, and sleep-disordered breathing (Sabo et al., 1991; Ağargün and Cartwright, 2003; Krakow et al., 2000). The failure to account for the effects of depression on sleep and suicide is a limitation in this literature. Although studies of depressed patient samples have provided evidence for a clear relationship between sleep and suicide, it remains unclear whether these findings would persist after controlling for depression. Although few studies have addressed this issue, there is some evidence supporting the relationship between suicidality and sleep problems, beyond the effect of depressive symptom severity (Keshavan et al., 1994; Smith et al., 2004; Bernert and Joiner, 2007) or chronicity of depressive symptoms (Chellappa and Araújo, 2007). Another limitation is that individuals suffering from sleep problems symptomatic of psychiatric distress rarely seek formal mental health treatment (Wojnar et al., 2009). For instance, less than 4% of individuals who suffer from insomnia report receiving any psychiatric services within the past 6 months (Weissman et al., 1997). Therefore, relying solely on the mental health field to detect individuals at risk may limit opportunities to effectively assess or intervene in other clinic populations. By extending suicide detection and early intervention efforts to other service providers, prevention efforts could be enhanced. One viable area of intervention would be outpatient sleep centers, which are equipped to treat individuals suffering from sleep disturbances that might impact suicidality (e.g., Krahn et al., 2008). To our knowledge, no studies have examined the association between sleep and suicide in large patient samples presenting at sleep clinics. Therefore, the first aim of the study was to explore the associations between a range of self-reported sleep problems and suicidal ideation in a sleep medical center population. Secondly, we examined whether associations remained after accounting for the possible influence of depressive symptoms. In light of past research, we anticipated that a broad array of sleep complaints and related symptoms would be associated with suicidal ideation and that several of these relationships would remain after controlling for severity of depressive symptoms.
2. Methods 2.1. Participants and procedure This study was a retrospective chart review reviewed and approved by the Los Alamos Medical Center IRB. Data were collected between January 2005 and June 2009. Patients were administered two waves of self-report measures: at intake and then between one and four weeks afterward. As only 55% of the sample completed both waves, we restricted the sample to include individuals who had data for both time points, yielding a convenience sample of 1584 participants. Refer to Table 1 for demographic data.
423
2.2. Measures 2.2.1. Sleep Medicine History (SMH; Krakow et al., 2001a,b) The SMH is a comprehensive self-report questionnaire that assesses a range of sleep-related concerns based on American Academy of Sleep Medicine (AASM) nosology. Information is collected on sleep indices, insomnia, sleep quality, sleep fragmentation factors, sleep-related daytime impairment, sleep-disordered breathing, restless legs syndrome, and periodic limb movement disorder. 2.2.2. Insomnia Severity Index (ISI; Bastien et al., 2001) The ISI is a seven-item self-report scale that assesses subjective symptoms of insomnia, including the degree of distress associated with each symptom. 2.2.3. Disturbing Dream and Nightmare Severity Index (DDNSI; Krakow, 2006) The DDNSI is a five-item self-report inventory designed to assess the frequency, severity, and intensity of nightmares. 2.2.4. Functional Outcomes Sleep Questionnaire (FOSQ ; Weaver et al., 1997) The FOSQ is a 30-item self-report measure designed to assess the effects of excessive daytime sleepiness on daily functioning. The FOSQ contains five subscales: general productivity, social outcome, activity level, intimacy/sexual functioning, and vigilance. 2.2.5. Quality of Life Enjoyment and Satisfaction QuestionnaireShort Form (Q-LES-Q ; Endicott et al., 1993) The Q-LES-Q is a self-report inventory designed to assess enjoyment and satisfaction in various areas of daily living. 2.2.6. Time Monitoring Behavior (TMB-10) The TMB-10 is a newly-constructed scale designed as a measure of time monitoring behavior and associated frustration. The ten-item scale is comprised of two subscales: the first, assessing time monitoring behavior related to sleep onset and the second, assessing behaviors associated with awakenings after sleep onset. Coefficient alpha in this sample was 0.95, indicating strong internal consistency. 2.2.7. Depressive Symptoms Inventory-Suicide Subscale (DSI-SS; Metalsky and Joiner, 1997) The DSI-SS consists of four self-report items focusing on frequency and intensity of suicidal thoughts and impulses during the past 2 weeks. 2.2.8. Hopkins Symptom Checklist (HSCL-25; Hesbacher, 2001) The HSCL-25 is designed as a screening assessment for anxiety and depression consisting of two subscales designed to measure these symptoms. 2.2.9. Psychiatric history As part of the intake procedures, individuals were asked to complete questionnaires that included questions about past psychiatric conditions, use of psychiatric medications, and psychotherapy experience.
424
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
Table 1 Sociodemographics & psychiatric history a. Characteristic
SI (n = 211)*
NSI (n = 1373)*
p, d, and differences of proportion values b
Age, years Gender Male Female Body mass index, Kg/m2 Marital status Married, living w/partner Single, divorced, or other Education Bachelors degree or higher Some college or lower Ethnicity Hispanic Caucasian Other Anxiety disorder Yes No Depression Yes No PTSD Yes No Trauma exposure Yes No
48.64 ± 11.85
49.93 ± 13.32
p = 0.18; d = 0.10
99 (46.9) 112 (53.1) 31.23 ± 8.96
766 (55.8) 607 (44.2) 30.78 ± 7.54
p = 0.01; 9% p = 0.43; d = 0.05
131 (62.4) 79 (37.6)
945 (69.0) 424 (31.0)
p = 0.03; 7%
118 (58.4) 84 (41.6)
757 (56.4) 585 (43.6)
p = 0.32; 2%
25 (11.9) 155 (73.9) 30 (14.3)
313 (22.8) 925 (67.4) 135 (9.8)
p = 0.001; 5%
93 (44.1) 118 (55.9)
264 (19.2) 1109 (80.8)
p = 0.001; 25%
148 (70.1) 63 (29.9)
463 (33.7) 910 (66.3)
p = 0.001; 37%
48 (22.7) 163 (77.3)
86 (6.3) 1287 (93.7)
p = 0.001; 16%
119 (56.7) 91 (43.3)
393 (28.8) 973 (71.2)
p = 0.001; 28%
Note. SI = Suicidal Ideation group; NSI = Non-suicidal Ideation group. a Dichotomous variables expressed as n(% of total) and continuous variables expressed as mean ± SD. b p value determined using χ2 analysis for dichotomous variables and One-Way ANOVA for continuous variables. Differences of Proportion are reported for dichotomous variables. Cohen's reported for continuous variables.
2.3. Data analysis The sample was first parsed into two groups based on DSISS total scores: individuals who presented endorsing suicidal ideation (i.e. DSI ≥ 1) were placed into the Suicidal Ideation (SI) group (n = 211). Patients who did not present with suicidal ideation (i.e. DSI-SS total score = 0) were placed in the No Suicidal Ideation (NSI) group (n = 1373). One-way ANOVA contrasted means between groups and Cohen's d was calculated for each comparison. Chi-square analyses were conducted on dichotomous variables and proportional differences between groups were calculated as effect sizes. Given that both sleep disturbances and suicidality are commonly associated with depression, we also explored the effects of suicidal ideation on sleep disturbance over and above the effects of depression. Using analysis of covariance (ANCOVA), we examined the differences in sleep disturbances between groups with level of depressive symptoms as measured by the HSCL-25 as a covariate. For these analyses, statistical significance was established at p ≤ 0.01 for all analyses. 3. Results Approximately 13.3% of participants reported suicidal ideation. Over one-third of those individuals reported clinically significant levels of suicidal ideation (i.e. 4.5% of the sample). Sleep problems were consistently associated with suicidality. Compared to the NSI group, the SI group
evidenced pervasive symptoms in a number of sleep-related domains (Table 2). On average, sleep problems were substantially more chronic in the SI group (F(1, 1501) = 29.34, p b 0.001); the SI group reported suffering from sleep problems for approximately 15 years (M = 15.24; SD = 13.08) and the NSI group reported suffering from sleep problems for just over a decade (M = 10.81 years; SD = 11.02). Insomnia symptoms were more severe in the SI group compared to the NSI group (F(1, 1582) = 75.16, p b 0.001). The SI group reported more awakenings per night (F(1, 1571) = 9.263, p b 0.01) and greater difficulty falling back to sleep (F(1, 1515) = 12.81, p b 0.001). Nightmares were more severe in the SI group (F(1, 1582) = 18.10, p b 0.001). Several areas of more severe sleep symptoms were present in the SI group compared to the NSI group for parasomnia behaviors, including “acting out dreams” (F(1, 1546) = 5.80, p = 0.01) and making disruptive noises during sleep (F(1, 1562) = 13.31, p b 0.001) as well as psychophysiological conditioning, including time monitoring behavior (F(1, 1583) = 50.98, p b 0.001), losing sleep over losing sleep (F(1, 1542) = 13.31, p b 0.001), and failing to create a positive sleep environment (F(1, 1251) = 10.03), p b 0.01). Not surprisingly, the SI group reported poorer subjective sleep quality as compared to the NSI group (F(1, 1582)= 21.79, p b 0.001). The SI group evidenced longer sleep onset latencies (F(1, 1549) = 7.551, p b 0.01) and longer time in bed (F(1, 1576) = 19.49, p b 0.01). Their sleep efficiency (percent of time asleep in bed), was also significantly worse than the NSI group
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
425
Table 2 Sleep disturbances associated with suicidal ideation. Characteristic
SI (n = 211)*
NSI (n = 1373)*
p, d, and Differences of Proportion values a
Insomnia symptoms Insomnia Severity Index (ISI) b, total score Total awakenings per night Trouble returning to sleep Yes No Subjective sleep indices Sleep onset latency, min. Total time in bed, h Wake after sleep onset, min. Sleep efficiency, % Sleep quality Subjective sleep c Quality Depth Visual analog scale d Sleepiness Tiredness Nightmare history Bad dreams or nightmares disrupt sleep Yes No DDNSI, total score Parasomnia symptomotology & psychophysiologic conditioning Acting out dreams/REM behavior disorder Yes No Disruptive noises/screaming during sleep Yes No Psychophysiologic conditioning TBM-10, total score Lose sleep over losing sleep Yes No Created a positive sleep environment Yes No Daily functioning & quality of life FOSQ , total score Q-LES-Q , total score
18.48 ± 5.70 3.62 ± 2.85
14.61 ± 6.08 3.15 ± 2.35
p = 0.001; d = 0.66 p = 0.01; d = 0.18
132 (63.2) 77 (36.8)
708 (51.9) 656 (48.1)
p = 0.001; 12%
75.46 ± 132.00 8.22 ± 2.13 109.14 ± 139.08 74.04 ± 23.29
45.59 ± 146.90 7.72 ± 1.43 74.87 ± 124.11 82.64 ± 24.80
p = 0.01; d = 0.21 p = 0.001; d = 0.28 p = 0.001; d = 0.13 p = 0.001; d = 0.36
4.89 ± 1.47 3.02 ± 1.37
4.38 ± 1.49 2.72 ± 1.24
p = 0.001; d = 0.34 p = 0.001; d = 0.23
6.55 ± 2.20 7.54 ± 2.08
5.79 ± 2.48 6.54 ± 2.39
p = 0.001; d = 0.32 p = 0.001; d = 0.45
73 (34.6) 138 (65.4) 7.12 ± 8.26
248 (18.1) 1120 (81.9) 3.32 ± 6.06
p = 0.001; 17% p = 0.001; d = 0.52
64 (31.1) 142 (68.9)
313 (23.3) 1028 (76.7)
p = 0.01; 8%
87 (42.2) 119 (57.8)
396 (29.6) 941 (70.4)
p = 0.001; 13%
16.89 ± 8.37
12.61 ± 8.08
p = 0.001; d = 0.52
94 (57.3) 70 (42.7)
333 (31.5) 724 (68.5)
p = 0.001; 26%
97 (56.7) 74 (43.3)
745 (68.9) 336 (31.1)
p = 0.001; 12%
12.62 + 3.56 47.80 + 10.71
15.36 ± 3.27 56.84 + 10.09
p = 0.001; d = 0.80 p = 0.001; d = 0.86
Note. SI = Suicidal Ideation group; NSI = Non-suicidal Ideation group. * Dichotomous variables expressed as n (% of total) and continuous variables expressed as mean ± SD. a p value determined using χ2 analysis for dichotomous variables and One-Way ANOVA for continuous variables. b ISI — Each question scored on scale of 0 to 4 based on increasing severity of the symptom, with total score ranges from 0 to 28. c Lower scores indicate a better response. d VAS Scales (sleepy and tired) — scored on a 0 to 10 metric with scores ≥7 indicative of severe symptoms.
(F(1, 1574)= 21.96, p b 0.001). Moreover, the SI group endorsed significantly lighter sleep (F(1, 1582) = 10.63, p = 0.001). The SI group also reported feeling sleepier (F(1, 1581) = 18.10, p b 0.001) and more fatigued (F(1, 1580)= 32.77, p b 0.001) during the day. The SI group also reported that their excessive sleepiness during the day had a greater impact on their daytime functioning (F(1, 1542) = 119.86, p b 0.001, d = 0.80). Relatedly, the SI group also reported poorer overall quality of life as compared to the non-SI group (F(1, 1573) = 144.31, p b 0.001, d = 0.86). In addition to sleep difficulties, the SI group also endorsed significantly greater psychopathology, including depression (F(1, 1582) = 109.32, p b 0.001). The SI group had a mean score of 1.4 (SD = 0.62) on the depression scale of the HSCL whereas the mean score for the NSI group was 0.66 (SD = 0.49). When controlling for the effects of depression,
the SI group evidenced more chronic sleep difficulties compared to the NSI group (F(1,1582) = 10.44, p b 0.001). Furthermore, the relationship between the presence of suicidal ideation and sleep quality also remained significant over and above the effects of depression, (F(1,1582) = 9.58, p b 0.05) such that the SI group also endorsed significantly poorer quality of sleep compared to the NSI group. Lastly, the SI group continued to evidence significantly higher levels of daily fatigue than the NSI group (F(1,1582) = 5.305, p = 0.021), over and above the effects of depression. Analyses also revealed several non-significant trends. Controlling for depression, analyses indicated that the SI group continued to have lighter sleep (F(1,1582) = 3.28, p = 0.07) as compared to the NSI group. Above and beyond the effects of depression, the SI group spent a longer time in bed (F(1, 1582) = 3.57, p = 0.06) than the NSI group.
426
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427
Analyses also indicated that the frequency of disturbing dreams and nightmares was greater in the SI group compared to the NSI group (F(1,1582) = 3.30, p = 0.07). 4. Discussion Suicidal ideation was endorsed by 13.3% of the present sample of sleep center patients. As expected, sleep disturbances were consistently associated with the presence of suicidal ideation. Suicidal individuals evidenced greater frequency and severity of various sleep problems as compared to non-suicidal individuals. By exploring effects of sleep on suicidal ideation when controlling for depression severity, our findings serve to replicate and extend the evidence for the unique contribution of sleep disturbances on suicide risk. Several sleep variables were significantly associated with suicidal ideation beyond the effects of depression. In particular, chronicity of sleep problems, daytime fatigue, and poor sleep quality are independently associated with suicidal ideation. These relationships fall in line with those of prior research (e.g., Wojnar et al., 2009; Aĝargün et al., 1997a,b; Turvey et al., 2002; Chellappa and Araújo, 2006). Certain sleep-focused interventions may be pertinent to treat sleep-disordered individuals experiencing suicidal ideation. Educating patients on basic sleep hygiene may improve quality of sleep. Stimulus control therapy, which focuses on reducing conditioned arousal associated with bedtime cues, as well as sleep restriction therapy are effective treatments for insomnia and may enhance sleep efficiency (Morin, 1993). Imagery rehearsal therapy is an effective treatment in reducing nightmares and disturbing dreams as well as decreasing insomnia symptoms (Krakow et al., 2001a,b). Together or separately, these sleep-focused interventions improve sleep quality problems, a key association observed in this study, and they are readily testable on populations reporting suicidal ideation. Examining the potential utility of these interventions in reducing suicidal ideation in sleep-disordered patients would be an important area for future research. Several limitations of are worth highlighting. First, the cross-sectional nature of the study precludes strong causal inferences. Future longitudinal studies designed to establish temporal precedence of the variables would be useful. Secondly, results may not generalize outside sleep center settings. In addition, the study is limited in that formal psychiatric diagnoses were not established. Given the reliability and validity of the HSCL-25, however, we would expect similar findings in patients formally diagnosed with MDD. Also, as a newly developed measure, the psychometric properties of the TMB-10 have not been well-established and further research is warranted on its reliability and validity. Lastly, definitive statements regarding the association between sleep variables and suicidal behavior cannot be made based on the current findings, given that the present study focused on suicidal ideation. Further research examining the relationships between sleep variables and suicidal behavior is crucial. Bearing in mind its limitations, the present study's findings have a number of clinical implications. First, collecting information about sleep would likely enhance suicide risk assessments. Furthermore, clinicians should be aware of the possibility that sleep disturbances may signal increased risk of suicidal ideation. Assessing the chronicity of sleep problems,
sleep quality, and daily fatigue would be most informative beyond assessing for depressive symptoms. Findings from the current investigation suggest that treating sleep difficulties may be a possible means of reducing associated risk of suicidal ideation; however, future research is necessary to evaluate this proposition. Disturbed sleep is a particularly promising area for intervention because it is easily modifiable through the use of medication or behavioral interventions. Evaluating the efficacy of sleep-focused interventions (e.g., sleep hygiene, stimulus control, and imagery rehearsal therapy) as a means of reducing risk of suicidal ideation would likely prove to be a promising line of future research. Role of funding source The present study did not have a funding source. Conflicts of interest Dr. Barry Krakow reported the following conflicts of interest: • 5 sites that provide education and offer products and services for sleep disorders patients: www.nightmaretreatment.com www.sleeptreatment.com www.sleepdynamictherapy.com www.soundsleepsoundmind.com www.nocturiacures.com www.ptsdsleepclinic.com • 3 books marketed and sold for sleep disorders patients: Insomnia Cures Turning Nightmares into Dreams Sound Sleep, Sound Mind • Ownership of one commercial sleep center: Maimonides Sleep Arts & Sciences, Ltd • Presidency of a non-profit sleep research center, the Sleep & Human Health Institute (www.shhi.org) that occasionally provides consultation services or receives grants for pilot studies, the most recent of which were: ∘ ConAlma. $5000 February, 2009 (sleep and obesity screening and education) ∘ Respironics, Inc $50,000 January, 2009 (study on prevalence of SDB in insomnia patients) ∘ GlaxoSmithKline $2500 July, 2008 (consulting on research on Breathe Right nasal strips) ∘ Covidien, Inc. $2500, August 2008 (consulting on PAP therapy devices) All other authors denied any possible conflict of interest with other people or organizations within 3 years of beginning the submitted work that could inappropriately influence the present research study.
Acknowledgements The authors have no acknowledgements. References Ağargün, M.Y., Cartwright, R., 2003. REM sleep, dream variables and suicidality in depressed patients. Psychiatry Res. 119 (1–2), 33–39. Aĝargün, M.Y., Kara, H., Solmaz, M., 1997a. Sleep disturbances and suicidal behavior in patients with major depression. J. Clin. Psychiatry 58 (6), 249–251. Aĝargün, M.Y., Kara, H., Solmaz, M., 1997b. Subjective sleep quality and suicidality in patients with major depression. J. Psychiatr. Res. 31 (3), 377–381. Ağargün, M.Y., Çilli, A.S., Kara, H., Tarhan, N., Kincir, F., Öz, K., 1998. Repetitive and frightening dreams and suicidal behavior in patients with major depression. Compr. Psychiatry 39 (4), 198–202. Ağargün, M.Y., Besiroglu, L., Cilli, A.S., Gulec, M., Aydin, A., Inci, R., Selvi, Y., 2007. Nightmares, suicide attempts, and melancholic features in patients with unipolar major depression. J. Affect. Disord. 98 (3), 267–270.
B. Krakow et al. / Journal of Affective Disorders 131 (2011) 422–427 Bastien, C.H., Vallieres, A., Morin, C.M., 2001. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Med. 2 (4), 297–307. Bernert, R.A., Joiner, T.E., 2007. Sleep disturbances and suicide risk: a review of the literature. Neuropsychiatr. Dis. Treat. 3 (6), 735–743. Borges, G., Angst, J., Nock, M., Ruscio, A., Kessler, R., 2008. Risk factors for the incidence and persistence of suicide-related outcomes: a 10-year followup study using the National Comorbidity Surveys. J. Affect. Disord. 10, 25–33. Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Web-based Injury Statistics Query and Reporting System (WISQARS). Retrieved from: www.cdc.gov/ncipc/wisqars. Chellappa, S.L., Araújo, J.F., 2006. Excessive daytime sleepiness in patients with depressive disorder. Rev. Bras. Psiquiatr. 28 (2), 1–7. Chellappa, S.L., Araújo, J.F., 2007. Sleep disorders and suicidal ideation in patients with depressive disorder. Psychiatry Res. 153 (2), 131–136. Endicott, J., Knee, J., Harrison, W., Blumenthal, R., 1993. Quality of Life Enjoyment and Satisfaction Questionnaire: a new measure. Psychopharmacol. Bull. 29, 321–326. Fawcett, J., Scheftner, W.A., Fogg, L., Clark, D.C., 1990. Time-related predictors of suicide in major affective disorder. Am. J. Psychiatry 147 (9), 1189–1194. Hesbacher, P.T., 2001. Psychiatric illness in family practice. J. Clin. Psychiatry 41 (1), 6–10. Keshavan, M.S., Reynolds, C.F., Montrose, D., Miewald, J., Downs, C., Sabo, E.J., 1994. Sleep and suicidality in psychotic patients. Acta Psychiatr. Scand. 89, 122–125. Kessler, R.C., Borges, G., Walters, E.E., 1999. Prevalence of and risk factors for lifetime suicide attempts in the national comorbidity survey. Arch. Gen. Psychiatry 56 (7), 617–626. Krahn, L.E., Miller, B.W., Bergstrom, L.R., 2008. Rapid resolution of intense suicidal ideation after treatment of severe obstructive sleep apnea. J. Clin. Sleep Med. 4 (1), 64–65. Krakow, B., 2006. Nightmare complaints in treatment-seeking patients in clinical sleep medicine settings: diagnostic and treatment implications. Sleep 29 (10), 1313–1319. Krakow, B., Artar, A., Warner, T.D., Melendrez, D., Johnston, L., Hollifield, M., Koss, M., 2000. Sleep disorder, depression and suicidality in female sexual assault survivors. Crisis J. Crisis Interv. Suicide Prev. 21 (4), 163– 170.
427
Krakow, B., Holliefield, M., Johnston, L., Koss, M., Schrader, R., Warner, T., Prince, H., 2001a. Imagery Rehearsal Therapy for chronic nightmares in sexual assault survivors with posttraumatic stress disorder. JAMA 286, 537–545. Krakow, B., Melendrez, D., Ferreira, E., Clark, J., Warner, T.D., Sisley, B., Sklar, D., 2001b. Prevalence of insomnia symptoms in patients with sleep-disordered breathing. Chest 120, 1923–1929. Mann, J.J., Apter, A., Bertolote, J., Beautrais, A., Currier, D., Haas, A., Hendin, H., 2005. Suicide prevention strategies: a systematic review. J. Am. Med. Assoc. 294, 2064–2074. Maris, R.M., 1992. Assessment and Prediction of Suicide. In: Maris, R.A., Berman, A.L., Maltsberger, J.T. (Eds.), Guilford Press, New York. Metalsky, G.I., Joiner Jr., T.E., 1997. The hopelessness depression symptom questionnaire. Cogn. Ther. Res. Spec. Issue Cogn. Pers. Subtypes Depress. 21 (3), 359–384. Morin, C.M., 1993. Insomnia: Psychological Assessment and Management. Guilford Press, New York. Sabo, E., Reynolds, C.F., Kupfer, D.J., Berman, S.R., 1991. Sleep, depression, and suicide. Psychiatry Res. 36 (3), 265–277. Smith, M.T., Perils, M.L., Haythornthwaite, J.A., 2004. Suicidal ideation in outpatients with chronic musculoskeletal pain: an exploratory study of the role of sleep onset insomnia and pain intensity. Clin. J. Pain 20 (2), 111–118. Tanskanen, A., Tuomilehto, J., Viinamäki, H., Vartiainen, E., Lehtonen, J., Puska, P., 2001. Nightmares as predictors of suicide. Sleep J. Sleep Sleep Disord. Res. 24 (7), 844–847. Turvey, C.L., Conwell, Y., Jones, M.P., Phillips, C., Simonsick, E., Pearson, J.L., Wallace, R., 2002. Risk factors for late-life suicide: a prospective community-based study. Am. J. Geriatr. Psychiatry Spec. Issue Suicidal Behaviors Older Adults 10 (4), 398–406. Weaver, T.E., Laizner, A., Evans, L.K., Maislin, G., Chugh, D.K., Lyons, K., Dinges, D.F., 1997. An instrument to measure functional status outcomes for disorders of excessive sleepiness. Sleep 20, 835–843. Weissman, M.M., Greenwald, S., Nino-Murcia, G., Dement, W.C., 1997. The morbidity of insomnia uncomplicated by psychiatric disorders. Gen. Hosp. Psyhiatry 19 (4), 245–250. Wojnar, M., Ilgen, M.A., Wojnar, J., McCammon, R.J., Valenstein, M., Brower, K.J., 2009. Sleep problems and suicidality in the national comorbidity survey replication. J. Psychiatr. Res. 43 (5), 526–531.