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Characteristics of Individuals Who Do or Do Not Seek Treatment for Chronic Insomnia
Characteristics of Individuals Who Do or Do Not Seek Treatment for Chronic Insomnia EDWARD STEPANSKI, PH.D., GAIL KOSHOREK, A.S.
FRANK ZoRICK, M.D., MICHELE GUNN,
B.A.
TIMOTHY ROEHRS, PH.D., THOMAS ROTH, PH.D.
Survey data have shown that a minority 0/ people who complain 0/ insomnia receive medicaltreatment/or this problem. Patients who seek treatment/or insomnia at medical clinics and sleep disorders centers are a self-selected group who may not be representative 0/ all individuals with insomnia. Fifty patients presenting to a sleep disorders center with an insomnia complaint were compared to 50 subjects with insomnia recruited through the newspaper/or psychopharmacological studies. No differences in sleep parameters were found. but significant differences on psychometric measures and in daytime alertness were present. The implications 0/ these differences are discussed.
nly a minority of people who complain of insomnia receive medical treabnent to improve their sleep. lOne important implication of this finding is that those patients treated in a medical clinic setting are only a small subgroup of all problem sleepers, and those individuals seen in sleep disorders centers constitute an even smaller subgroup. This raises the possibility that patients receiving treabnent may have different characteristics than insomniacs in general. Yet much of the research on the evaluation and treatment of insomnia complaints uses members of this subgroup as subjects. Accurate interpretation of research aimed at furthering understanding of the nature and causes of insomnia relies on an appreciation of potential differences in characteristics of the samples studied. For instance, evaluations of the efficacy of hypnotic compounds use sleep studies as an important component of the assessment process. These trials require recruibnent from the general population of both subjects with insomnia and normal sleepers. Individuals with insomnia who volunteer for a research study may represent a subgroup of insomniacs different from those to
O
VOLUME 30· NUMBER 4· FALL 1989
which the results of the studies are generalized. We conducted a preliminary study of sleep parameters and daytime functioning in 15 patients referred to our sleep-disorders clinic for evaluation of insomnia and 15 age-matched insomnia-research subjects. 2 No statistically significant differences between groups were found for any sleep measure except the percentage of stage REM (rapid eye movement) sleep. Patients referred to the clinic had significantly more variability on sleep measures than the subjects recruited through the research program. Significant differences between groups were also found on the Minnesota Multiphasic Personality Inventory (MMPI).3 Patients referred to the clinic scored significantly higher on five MMPI scales (Hs, D, Hy, Pt, and Sc); they also had signifiReceived February 3. 1988; revised July 20. 1988; accepled Augusl 11, 1988. From !he Sleep Disorders and Research Cenler, Henry Ford Hospilal, Derroil. Michigan. Address reprinl requests 10 Dr. Slepanski. Sleep Disorders and Research Cenler, Henry Ford Hospilal, 2921 West Grand Boulevard, Derroil, MI 48202. Copyright C> 1989 The Academy of Psychosomalic Medicine.
421
Treatment-Seeking for Insomnia
TABLE 1. Sleep parameters of self-referred and physician-referred individuals with Insomn""ln mean±SD minutes Self-referred Physician-referred Group Group 403.3±54.4
402. 1±I03. t".
Average lalency stage-2 sleep
45.6±37.8
42.4±56.f·
Percent stage-I sleep
17.0±8.9
16.2±9.1
Percent stage-2 sleep
54.9±8.6
54.5±1O.I
8.6±9.2
11.3±8.7
Percent stageREM sleep
19.4±6.5
18.0±7.3
Wakefulness during sleep
35.3±36.4
64.7t49.4
Total sleep time
Percent stage-3/4 sleep
.
·p<.OOOI; "p<.006; ···p<.OOI
cantly more scales with elevated scores (MMPI standard scores ofT>70) than the research group. The study reported here extends our earlier study. We used a larger sample and attempted to decrease the variability by selecting subjects who were more homogeneous with respect to age and sex. Most important, measures of various aspects of daytime functioning were expanded. METHODS Subjects Fifty patients evaluated for insomnia in our sleep-disorders clinic composed the clinic group. The patients were referred to the clinic by their physicians, and they had had insomnia for at least six months before we evaluated them. Fifty subjects with sleeping difficulties who had been recruited from the general public for a study of hypnotic efficacy constituted the self-referred group. The mean±SD age of the physician-referred group was 34.3± I0.2; the mean±SD age of the research group was 34.1±7.0. There were 32 men and 18 women in both groups. Educational level was the same for both groups. 422
Procedures The evaluation included a sleep history, a psychiatric history, a clinical polysomnogram, a multiple sleep latency test (MSLT), a psychometric battery consisting of the MMPI, Profile of Mood States (POMS),4 and the Cornell Medical Index (CMI),s and an insomnia questionnaire that we developed. The MSLT provides an objective measure of daytime sleepiness. The Cornell Medical Index consists of two symptom checklists divided between emotional and physical symptoms. Exclusion criteria included having an acute medical or psychiatric illness, working rotating shifts so that hours of sleep varied from day to day, or having a schedule that required sleeping during the day. Evaluation of sleep complaints of patients with acute illness (i.e., major affective illness or congestive heart failure) was not indicated until their medical or psychiatric disorder was treated; therefore, polysomnography was not performed, and they were not included in the present protocol. All other patients who completed the evaluation participated. The polysomnographic recording consisted of two electroencephalograph (EEG) channels (C3/A2 and OZ/A2), electro-oculograms (EOG) of the right and left orbits, and electromyograms (EMG) of the chin and both legs. Respiration was measured with a nasaVoral thermistor. Subjects went to bed in the sleep laboratory at their regular bedtimes. They remained in bed for eight hours and EEG, EOG, and EMG recordings were taken continuously. Sleep stages were scored according to standard criteria.6 Nighttime data are from the first night in the laboratory for both groups. Objective sleep parameters were not used as exclusion criteria for either group. The physicianreferred group was given an MSLT immediately following their first night's recording; the research group was given a MSLT after its third sleep recording. RESULTS The data were analyzed using (-tests for independent groups for each of the sleep parameters, the MSLT, and the psychometric scores. A chiPSYCHOSOMATICS
Stepanski et al.
square analysis was used on frequency data generated by responses on the insomnia questionnaire. An alpha level of .025 was used as a measure of significance. Sleep Parameters Analysis of the sleep data showed that the two groups did not differ significantly in total sleep time (TST). Both groups slept approximately 6.5 hours pernight (see Table 1). Average latencies to stage 2 sleep6 were nearly identical: 42.7 minutes for the physician-referred group and 43.7 minutes for the self-referred group. The physician-referred subjects had an average time of wakefulness during sleep (WDS) of 64.7 minutes, significantly more than the average of 35.3 minutes in the self-referred group. Sleep staging was similar in both groups, but physician-referred subjects experienced more stage 3/4 sleep. Greater variability in sleep parameters was found in the physician-referred group. They had larger standard deviations for almost every sleep parameter, and the differences were statistically significant for total sleep time, wake before sleep (WBS) or time awake before stage 2 sleep, and latency to stage 2 sleep. Daytime Functioning The mean MSLT score for physician-referred patients was 13.9 minutes; the mean MSLT score for self-referred subjects was 11.4 minutes. This difference was significant (see Table 2). When individual naps were assessed, only the length of nap 1 was significantly different for the two groups. The self-referred group had an average latency of 11.3 minutes to sleep, and the physician-referred group had an average latency of 14.5 minutes. Although the MSLTwas performed after the third night in self-referred patients, sleep parameters from the third night were not significantly different from sleep parameters from the frrst night for this group, and results from the MSLT were therefore representative. The physician-referred patients scored higher than the self-referred group on all POMS VOLUME 30· NUMBER 4· FALL 1989
TABLE 2. Results of multiple sleep latency tests (MSLT) for self-referred and physicianreferred individuals with Insomnia, by mean±SD mlnutes" Self-Referred Physician-Referred Group Group
Mean MSLT latency
11.35±5.46
Nap I
11.2S±6.96
14.46±5.66·
Nap 2
11.4St7.03
13.4S±5.S7
Nap 3 Nap 4
1O.79±6.S2
13.07±5.74
II.77t7.0S
14.57±6.24
13.S9t4.42"
·p<.02 "Results indicate time elapsed before falling asleep. TABLE 3. Mean±SD scores 011 the Proftle for Mood States (POMS) and Cornell Medlcal Index for self-referred and physician-referred patients with Insomnia Self-Referred Physician-Referred Group Group
Index
Proftle of Mood States tension 35.S±8.9
45.2±7.6··
4O.7tS.2
43.6±7.6" 47.5t7.6··
fatigue
41.9±6.6
53.8±7.S··
vigor
5S.7tI2.6
52.2±9.0·
37.6±5.S
43.9±7.S··
depression anger
confusion
37.7±6.3
Cornell Medical Index
physical scale emotional scale ·p<'()05;
19.3t45.5
5.0tS.7
25.ltI3.5 12.6··±8.S·
··p<.OOOI
scales (see Table 3). They also scored higher on the emotional scale and the physical scale of the
eMI. On the MMPI, the physician-referred patients scored significantly higher than the self-referred group on scales Hs, D, Hy, Pt, and Ma. The physician-referred patients also had a greater mean number ofelevated scores (2.71) overall on the MMPI than did the self-referred subjects (1.59)(see Figure I). To control for the effects of psychopathology, the MMPI data were reanalyzed excluding data from nine patients who had received diagnoses of insomnia secondary to a psychiatric condition (affective disorder, anxiety 423
Treatment-Seeking for Insomnia
FIGURE I. Mean scores on scales of the Minnesota Muhiphaslc Personality Inventory for physician-referred patients and self-referred subjects with Insomnia
80
••• <>
•./ "*0·
70
~
<> 60
50
l't
••• <>
+-+-+
i.~~ <>
<> - <>
Physician-referred Patients (n=45)
+- + Self-referred Subjects (n=47)
40 +--+-:-I--lf--.......--f.--I-.-l.I--f--+.-+---'I--f~ ......- - t L F K Us D Uy Pd Pa Pl Sc Ma • p ( 0.004••• P ( 0.0002•••• P (0.0001
disorder, or personality disorder). The results from reanalysis were virtually identical to those of the overall analysis (see Figure 2). Scores on scales Hs, D, Hy, Pt, and Ma remained significantly different, and the absolute levels of the mean scores were the same. The insomnia-questionnaire data exploring dimensions of the insomnia complaint, daytime sequelae, and sedative use were also analyzed (see Table 4). Both groups reported having insomnia for approximately the same length of time, but the physician-referred patients reported that the insomnia had been more severe recently and that they experienced it more often (average 6.26 nights a week) than the self-referred subjects (average 5.14 nights a week). The physician-referred patients were also significantly more likely to take sedatives; 50% of the physician-referred group had taken a prescribed hypnotic within two months of the study, compared to only 6% of the self-referred group (X 2=23.7, p<.OO I). As part of the insomnia questionnaire, subjects were asked to indicate on a checklist which symptoms they experienced during the day as a 424
result of bad sleep. The list consisted of depressed, tired, anxious, irritable, physically worse, sleepy, light-headed, tense, and other (for example, headache or nausea). The physician-referred patients reported an average of 4.6 symptoms, compared with three symptoms by the self-referred group. Tiredness, irritability, and sleepiness were the most frequently reported symptoms by both groups. Significantly more subjects in the physician-referred group complained of depression, anxiety, irritability, and light-headedness than did members ofthe self-referred group (see Table 5). DISCUSSION The results from this expanded study are consistent with the results of the preliminary study. Objective sleep quantity and quality were essentially the same for both physician-referred and self-referred patients, but significantly greater variability in total sleep time and latency time to sleep was found in physician-referred patients. In contrast to the congruence of the sleep PSYCHOSOMATICS
Stepanski et al.
data, marked differences on measures of waking function were found between physician-referred and self-referred subjects. The physician-referred subjects had more scores in the pathological range on all psychometric measures than did self-referred subjects, although not all of the selfTABLE 4. Characteristics of Insomnia reported by self-referred and physician-rderred patients with Insomnia
Duration (mean±SD years)
12.4±11.5
11.4±IO.7
Duration at current level of severity (mean±SD years)
7.4±9.0
Nights per week (mean±SD number)
5.ltl.l
6.3±I.O"-
Daytimesymptoms (mean±SD number)
3.1±1.7
4.6±1.9--
3.2±3.7-
-p<.OO7; --p<.OOI; -"p<.OOOI
TABLE S. Daytime symptoms of self-referred and physician-referred patients with Insomnia, by percentage of patients with symptom Daytime Symptom
Self-Referred Physician-Referred Group Group
Characteristics
referred group's scores were in the normal range. As a group, physician-referred patients displayed greater psychological turmoil and discomfort,
Self-Referred Physician-Referred Group Group 57%28%
Depression Fatigue Anxiety Irritability Physical deterioration Sleepiness Light-headedness Tension Other"
76% 22% 48% 14%
87% 44%-
12%
74% 26% 57% 35%-
34% 16%
48% 35%
60%
"'Ibis category included. for example. nausea and headache. -p<.02
FIGURE 2. Mean scores on scales of the Minnesota Multiphasic Personality Inventory for physician-referred patients and self·referred subjects with Insomnia. Scores or nine patients who had received a diagnosis of Insomnia secondary to a psychiatric condition have been removed and the means recalculated.
80
I"
70
60
50
0-0
Physidan-referred Patients without Psychiatric Disorders (n=36)
• - . self-referred Subjects (n=47)
40 +--t--+---;--t--t--f-'-+--+---l--+---f--t---It-~. L F K Hs D Hy Pd Pa Pt Sc Ma • p ( 0.001••• p(0.0004•••• p(O.OOOl
VOLUME 30 - NUMBER 4 - FALL 1989
425
Treatment-Seeking for Insomnia
and these were expressed as higher scores on the depression and psychasthenia scales. This finding is consistent with results from other studies7 •8 that compared patients complaining of insomnia to subjects with normal sleep patterns. These studies found that subjects from the clinics had more abnormal scores on psychometric tests. The self-referred group in our study experienced the same sleep disturbances that the physician-referred patients experienced. but the waking function of self-referred subjects more closely approximated waking function seen in normal control subjects. Indeed. a study that pooled data from 138 subjects complaining of insomnia who participated in psychopharmacological studies (a group analogous to the self-referred group in our study) failed to find differences between subjects with insomnia and normal controls on the MMPI or on the POMS. even though significant differences in total sleep time and latency to sleep were found. 9 Another measure of waking function. the MSLT. also revealed significant differences between the groups. Physician-referred patients were significantly more alert during the day than self-referred patients. In a previous study.1O we had found that patients evaluated through the sleep-disorders clinic were significantly more alert during the day than asymptomatic controls. indicating that the research subjects were more like normal subjects with respect to waking function. despite their objective sleep disturbance. In a previous study. we lO had found that patients recruited through a sleep-disorders clinic (subjects analogous to our physician-referred group) were significantly more alert during the day than normal control subjects. The self-referred subjects in the study reported here showed daytime alertness similar to alertness in normal controls.
However. the self-referred subjects did not have normal results on the MSLT. Mean time-to-sleep latencies on the MSLT were similar for normal controls and self-referred subjects. but because the self-referred group sleeps less than the normal controls, the self-referred subjects should be more sleepy. The MSLT results suggest that the self-referred group is hyperaroused, but to a lesser extent than the physician-referred group. The hyperarousal demonstrated on the MSLT may be related to the constructs of "autonomic arousal" or"somatized tension" previously found in individuals with insomnia on psychophysiological and psychometric measures. li - 13 One important conclusion of our current study is that patients who are referred to a sleep center because of insomnia are a highly self-selected group. If the physician-referred and selfreferred groups are viewed together as an overall insomnia group, then the present data suggest that individuals with daytime distress present for treatment of their poor sleep. Other subjects who experience equally poor sleep but who do not have psychological symptoms do not seek treatment. There are two potential explanations for the increased psychological distress in those seeking treatment: physician-referred patients may represent a subgroup of individuals who are more sensitive to the effects of chronic insomnia; they may therefore have more sequelae, which drive them to seek help. An alternative explanation is that the physician-referred subjects are actually seeking relief from their psychological symptoms, which they perceive to be related to their poor sleep. In fact, the symptom checklist data described above show that the physician-referred group directly attributes their disturbed mood to their insomnia.
References
I. Mellinger GO. Balter MB. Uhlenhuth EH: Insomnia and its treatment: prevalence and correlates. Arch Gen Psychiatry 42:225-232. 1985 2. Stepanski E. Koshorek G. Zorick F. et a1: Sleep and personality characteristics of patients and subjects with chronic complaints of insomnia. Sleep Research 16:439. 1987 426
3. Hathaway SR. McKinley JC: Minnesota Multiphasic Personality Inventory. Minneapolis. University ofMinnesota Press. 1943 4. McNair OM. Lorr M. Droppleman LF: ErrS Manual for the Profile of Mood States. San Diego. Educational and Industrial Testing Service. 1971 5. Brodman K. Erdmann AJ. Lorge I. et a1: The Cornell PSYCHOSOMATICS
Stepanski et al.
Medicallndex.JAMA 140:530. 1949 6. RechlSChaffen A. Kales A: A Manual of Standardized Terminology. Techniques and Scoring System for Sleep Stages of Human Subjects. Los Angeles. Brain Informa·
tion ServicelBrain Research Institute. University ofCalifornia at Los Angeles Press. 1968 7. Zorick F. Roth T. Hanse K. et aI: Evaluation and diagnosis of persistent insomnia. Am J Psychiatry 138:769-773. 1981 8. Kales A. Caldwell A. Soldatos C. et aI: Biobehavioral correlates of insomnia: II. pattern specificity and consistency with the Minnesota Multiphasic Personality Inven· tory. Psychosom Med 45:341-356. 1983 9. Seidel WF. Ball S. Cohen S. et aI: Daytime alenness in
VOLUME 30· NUMBER 4· FAll 1989
relation to mood. performance. and nocturnal sleep in chronic insomniacs and noncomplaining sleepers. Sleep 3:230-258.1984 10. Stepanski E. Zorick F. Roehrs T. et aI: Daytime alenness in patients with chronic insomnia compared with asymptomatic control subjects. Sleep I I:54-{)(). 1988 II. Monroe U: Psychological and physiological differences between good and poor sleepers. J Abnorm Psychol 72:255-264.1967 12. Hauri P. Fisher J: Persistent psychophysiologic (learned) insomnia. Sleep 9:38-53. 1986 13. Freedman R. Sattler H: Physiological and psychological factors in sleep-onset insomnia. J Abnorm Psychol 91:380-389.1982
427
FRANK ZoRICK, M.D., MICHELE GUNN,
B.A.
TIMOTHY ROEHRS, PH.D., THOMAS ROTH, PH.D.
Survey data have shown that a minority 0/ people who complain 0/ insomnia receive medicaltreatment/or this problem. Patients who seek treatment/or insomnia at medical clinics and sleep disorders centers are a self-selected group who may not be representative 0/ all individuals with insomnia. Fifty patients presenting to a sleep disorders center with an insomnia complaint were compared to 50 subjects with insomnia recruited through the newspaper/or psychopharmacological studies. No differences in sleep parameters were found. but significant differences on psychometric measures and in daytime alertness were present. The implications 0/ these differences are discussed.
nly a minority of people who complain of insomnia receive medical treabnent to improve their sleep. lOne important implication of this finding is that those patients treated in a medical clinic setting are only a small subgroup of all problem sleepers, and those individuals seen in sleep disorders centers constitute an even smaller subgroup. This raises the possibility that patients receiving treabnent may have different characteristics than insomniacs in general. Yet much of the research on the evaluation and treatment of insomnia complaints uses members of this subgroup as subjects. Accurate interpretation of research aimed at furthering understanding of the nature and causes of insomnia relies on an appreciation of potential differences in characteristics of the samples studied. For instance, evaluations of the efficacy of hypnotic compounds use sleep studies as an important component of the assessment process. These trials require recruibnent from the general population of both subjects with insomnia and normal sleepers. Individuals with insomnia who volunteer for a research study may represent a subgroup of insomniacs different from those to
O
VOLUME 30· NUMBER 4· FALL 1989
which the results of the studies are generalized. We conducted a preliminary study of sleep parameters and daytime functioning in 15 patients referred to our sleep-disorders clinic for evaluation of insomnia and 15 age-matched insomnia-research subjects. 2 No statistically significant differences between groups were found for any sleep measure except the percentage of stage REM (rapid eye movement) sleep. Patients referred to the clinic had significantly more variability on sleep measures than the subjects recruited through the research program. Significant differences between groups were also found on the Minnesota Multiphasic Personality Inventory (MMPI).3 Patients referred to the clinic scored significantly higher on five MMPI scales (Hs, D, Hy, Pt, and Sc); they also had signifiReceived February 3. 1988; revised July 20. 1988; accepled Augusl 11, 1988. From !he Sleep Disorders and Research Cenler, Henry Ford Hospilal, Derroil. Michigan. Address reprinl requests 10 Dr. Slepanski. Sleep Disorders and Research Cenler, Henry Ford Hospilal, 2921 West Grand Boulevard, Derroil, MI 48202. Copyright C> 1989 The Academy of Psychosomalic Medicine.
421
Treatment-Seeking for Insomnia
TABLE 1. Sleep parameters of self-referred and physician-referred individuals with Insomn""ln mean±SD minutes Self-referred Physician-referred Group Group 403.3±54.4
402. 1±I03. t".
Average lalency stage-2 sleep
45.6±37.8
42.4±56.f·
Percent stage-I sleep
17.0±8.9
16.2±9.1
Percent stage-2 sleep
54.9±8.6
54.5±1O.I
8.6±9.2
11.3±8.7
Percent stageREM sleep
19.4±6.5
18.0±7.3
Wakefulness during sleep
35.3±36.4
64.7t49.4
Total sleep time
Percent stage-3/4 sleep
.
·p<.OOOI; "p<.006; ···p<.OOI
cantly more scales with elevated scores (MMPI standard scores ofT>70) than the research group. The study reported here extends our earlier study. We used a larger sample and attempted to decrease the variability by selecting subjects who were more homogeneous with respect to age and sex. Most important, measures of various aspects of daytime functioning were expanded. METHODS Subjects Fifty patients evaluated for insomnia in our sleep-disorders clinic composed the clinic group. The patients were referred to the clinic by their physicians, and they had had insomnia for at least six months before we evaluated them. Fifty subjects with sleeping difficulties who had been recruited from the general public for a study of hypnotic efficacy constituted the self-referred group. The mean±SD age of the physician-referred group was 34.3± I0.2; the mean±SD age of the research group was 34.1±7.0. There were 32 men and 18 women in both groups. Educational level was the same for both groups. 422
Procedures The evaluation included a sleep history, a psychiatric history, a clinical polysomnogram, a multiple sleep latency test (MSLT), a psychometric battery consisting of the MMPI, Profile of Mood States (POMS),4 and the Cornell Medical Index (CMI),s and an insomnia questionnaire that we developed. The MSLT provides an objective measure of daytime sleepiness. The Cornell Medical Index consists of two symptom checklists divided between emotional and physical symptoms. Exclusion criteria included having an acute medical or psychiatric illness, working rotating shifts so that hours of sleep varied from day to day, or having a schedule that required sleeping during the day. Evaluation of sleep complaints of patients with acute illness (i.e., major affective illness or congestive heart failure) was not indicated until their medical or psychiatric disorder was treated; therefore, polysomnography was not performed, and they were not included in the present protocol. All other patients who completed the evaluation participated. The polysomnographic recording consisted of two electroencephalograph (EEG) channels (C3/A2 and OZ/A2), electro-oculograms (EOG) of the right and left orbits, and electromyograms (EMG) of the chin and both legs. Respiration was measured with a nasaVoral thermistor. Subjects went to bed in the sleep laboratory at their regular bedtimes. They remained in bed for eight hours and EEG, EOG, and EMG recordings were taken continuously. Sleep stages were scored according to standard criteria.6 Nighttime data are from the first night in the laboratory for both groups. Objective sleep parameters were not used as exclusion criteria for either group. The physicianreferred group was given an MSLT immediately following their first night's recording; the research group was given a MSLT after its third sleep recording. RESULTS The data were analyzed using (-tests for independent groups for each of the sleep parameters, the MSLT, and the psychometric scores. A chiPSYCHOSOMATICS
Stepanski et al.
square analysis was used on frequency data generated by responses on the insomnia questionnaire. An alpha level of .025 was used as a measure of significance. Sleep Parameters Analysis of the sleep data showed that the two groups did not differ significantly in total sleep time (TST). Both groups slept approximately 6.5 hours pernight (see Table 1). Average latencies to stage 2 sleep6 were nearly identical: 42.7 minutes for the physician-referred group and 43.7 minutes for the self-referred group. The physician-referred subjects had an average time of wakefulness during sleep (WDS) of 64.7 minutes, significantly more than the average of 35.3 minutes in the self-referred group. Sleep staging was similar in both groups, but physician-referred subjects experienced more stage 3/4 sleep. Greater variability in sleep parameters was found in the physician-referred group. They had larger standard deviations for almost every sleep parameter, and the differences were statistically significant for total sleep time, wake before sleep (WBS) or time awake before stage 2 sleep, and latency to stage 2 sleep. Daytime Functioning The mean MSLT score for physician-referred patients was 13.9 minutes; the mean MSLT score for self-referred subjects was 11.4 minutes. This difference was significant (see Table 2). When individual naps were assessed, only the length of nap 1 was significantly different for the two groups. The self-referred group had an average latency of 11.3 minutes to sleep, and the physician-referred group had an average latency of 14.5 minutes. Although the MSLTwas performed after the third night in self-referred patients, sleep parameters from the third night were not significantly different from sleep parameters from the frrst night for this group, and results from the MSLT were therefore representative. The physician-referred patients scored higher than the self-referred group on all POMS VOLUME 30· NUMBER 4· FALL 1989
TABLE 2. Results of multiple sleep latency tests (MSLT) for self-referred and physicianreferred individuals with Insomnia, by mean±SD mlnutes" Self-Referred Physician-Referred Group Group
Mean MSLT latency
11.35±5.46
Nap I
11.2S±6.96
14.46±5.66·
Nap 2
11.4St7.03
13.4S±5.S7
Nap 3 Nap 4
1O.79±6.S2
13.07±5.74
II.77t7.0S
14.57±6.24
13.S9t4.42"
·p<.02 "Results indicate time elapsed before falling asleep. TABLE 3. Mean±SD scores 011 the Proftle for Mood States (POMS) and Cornell Medlcal Index for self-referred and physician-referred patients with Insomnia Self-Referred Physician-Referred Group Group
Index
Proftle of Mood States tension 35.S±8.9
45.2±7.6··
4O.7tS.2
43.6±7.6" 47.5t7.6··
fatigue
41.9±6.6
53.8±7.S··
vigor
5S.7tI2.6
52.2±9.0·
37.6±5.S
43.9±7.S··
depression anger
confusion
37.7±6.3
Cornell Medical Index
physical scale emotional scale ·p<'()05;
19.3t45.5
5.0tS.7
25.ltI3.5 12.6··±8.S·
··p<.OOOI
scales (see Table 3). They also scored higher on the emotional scale and the physical scale of the
eMI. On the MMPI, the physician-referred patients scored significantly higher than the self-referred group on scales Hs, D, Hy, Pt, and Ma. The physician-referred patients also had a greater mean number ofelevated scores (2.71) overall on the MMPI than did the self-referred subjects (1.59)(see Figure I). To control for the effects of psychopathology, the MMPI data were reanalyzed excluding data from nine patients who had received diagnoses of insomnia secondary to a psychiatric condition (affective disorder, anxiety 423
Treatment-Seeking for Insomnia
FIGURE I. Mean scores on scales of the Minnesota Muhiphaslc Personality Inventory for physician-referred patients and self-referred subjects with Insomnia
80
••• <>
•./ "*0·
70
~
<> 60
50
l't
••• <>
+-+-+
i.~~ <>
<> - <>
Physician-referred Patients (n=45)
+- + Self-referred Subjects (n=47)
40 +--+-:-I--lf--.......--f.--I-.-l.I--f--+.-+---'I--f~ ......- - t L F K Us D Uy Pd Pa Pl Sc Ma • p ( 0.004••• P ( 0.0002•••• P (0.0001
disorder, or personality disorder). The results from reanalysis were virtually identical to those of the overall analysis (see Figure 2). Scores on scales Hs, D, Hy, Pt, and Ma remained significantly different, and the absolute levels of the mean scores were the same. The insomnia-questionnaire data exploring dimensions of the insomnia complaint, daytime sequelae, and sedative use were also analyzed (see Table 4). Both groups reported having insomnia for approximately the same length of time, but the physician-referred patients reported that the insomnia had been more severe recently and that they experienced it more often (average 6.26 nights a week) than the self-referred subjects (average 5.14 nights a week). The physician-referred patients were also significantly more likely to take sedatives; 50% of the physician-referred group had taken a prescribed hypnotic within two months of the study, compared to only 6% of the self-referred group (X 2=23.7, p<.OO I). As part of the insomnia questionnaire, subjects were asked to indicate on a checklist which symptoms they experienced during the day as a 424
result of bad sleep. The list consisted of depressed, tired, anxious, irritable, physically worse, sleepy, light-headed, tense, and other (for example, headache or nausea). The physician-referred patients reported an average of 4.6 symptoms, compared with three symptoms by the self-referred group. Tiredness, irritability, and sleepiness were the most frequently reported symptoms by both groups. Significantly more subjects in the physician-referred group complained of depression, anxiety, irritability, and light-headedness than did members ofthe self-referred group (see Table 5). DISCUSSION The results from this expanded study are consistent with the results of the preliminary study. Objective sleep quantity and quality were essentially the same for both physician-referred and self-referred patients, but significantly greater variability in total sleep time and latency time to sleep was found in physician-referred patients. In contrast to the congruence of the sleep PSYCHOSOMATICS
Stepanski et al.
data, marked differences on measures of waking function were found between physician-referred and self-referred subjects. The physician-referred subjects had more scores in the pathological range on all psychometric measures than did self-referred subjects, although not all of the selfTABLE 4. Characteristics of Insomnia reported by self-referred and physician-rderred patients with Insomnia
Duration (mean±SD years)
12.4±11.5
11.4±IO.7
Duration at current level of severity (mean±SD years)
7.4±9.0
Nights per week (mean±SD number)
5.ltl.l
6.3±I.O"-
Daytimesymptoms (mean±SD number)
3.1±1.7
4.6±1.9--
3.2±3.7-
-p<.OO7; --p<.OOI; -"p<.OOOI
TABLE S. Daytime symptoms of self-referred and physician-referred patients with Insomnia, by percentage of patients with symptom Daytime Symptom
Self-Referred Physician-Referred Group Group
Characteristics
referred group's scores were in the normal range. As a group, physician-referred patients displayed greater psychological turmoil and discomfort,
Self-Referred Physician-Referred Group Group 57%28%
Depression Fatigue Anxiety Irritability Physical deterioration Sleepiness Light-headedness Tension Other"
76% 22% 48% 14%
87% 44%-
12%
74% 26% 57% 35%-
34% 16%
48% 35%
60%
"'Ibis category included. for example. nausea and headache. -p<.02
FIGURE 2. Mean scores on scales of the Minnesota Multiphasic Personality Inventory for physician-referred patients and self·referred subjects with Insomnia. Scores or nine patients who had received a diagnosis of Insomnia secondary to a psychiatric condition have been removed and the means recalculated.
80
I"
70
60
50
0-0
Physidan-referred Patients without Psychiatric Disorders (n=36)
• - . self-referred Subjects (n=47)
40 +--t--+---;--t--t--f-'-+--+---l--+---f--t---It-~. L F K Hs D Hy Pd Pa Pt Sc Ma • p ( 0.001••• p(0.0004•••• p(O.OOOl
VOLUME 30 - NUMBER 4 - FALL 1989
425
Treatment-Seeking for Insomnia
and these were expressed as higher scores on the depression and psychasthenia scales. This finding is consistent with results from other studies7 •8 that compared patients complaining of insomnia to subjects with normal sleep patterns. These studies found that subjects from the clinics had more abnormal scores on psychometric tests. The self-referred group in our study experienced the same sleep disturbances that the physician-referred patients experienced. but the waking function of self-referred subjects more closely approximated waking function seen in normal control subjects. Indeed. a study that pooled data from 138 subjects complaining of insomnia who participated in psychopharmacological studies (a group analogous to the self-referred group in our study) failed to find differences between subjects with insomnia and normal controls on the MMPI or on the POMS. even though significant differences in total sleep time and latency to sleep were found. 9 Another measure of waking function. the MSLT. also revealed significant differences between the groups. Physician-referred patients were significantly more alert during the day than self-referred patients. In a previous study.1O we had found that patients evaluated through the sleep-disorders clinic were significantly more alert during the day than asymptomatic controls. indicating that the research subjects were more like normal subjects with respect to waking function. despite their objective sleep disturbance. In a previous study. we lO had found that patients recruited through a sleep-disorders clinic (subjects analogous to our physician-referred group) were significantly more alert during the day than normal control subjects. The self-referred subjects in the study reported here showed daytime alertness similar to alertness in normal controls.
However. the self-referred subjects did not have normal results on the MSLT. Mean time-to-sleep latencies on the MSLT were similar for normal controls and self-referred subjects. but because the self-referred group sleeps less than the normal controls, the self-referred subjects should be more sleepy. The MSLT results suggest that the self-referred group is hyperaroused, but to a lesser extent than the physician-referred group. The hyperarousal demonstrated on the MSLT may be related to the constructs of "autonomic arousal" or"somatized tension" previously found in individuals with insomnia on psychophysiological and psychometric measures. li - 13 One important conclusion of our current study is that patients who are referred to a sleep center because of insomnia are a highly self-selected group. If the physician-referred and selfreferred groups are viewed together as an overall insomnia group, then the present data suggest that individuals with daytime distress present for treatment of their poor sleep. Other subjects who experience equally poor sleep but who do not have psychological symptoms do not seek treatment. There are two potential explanations for the increased psychological distress in those seeking treatment: physician-referred patients may represent a subgroup of individuals who are more sensitive to the effects of chronic insomnia; they may therefore have more sequelae, which drive them to seek help. An alternative explanation is that the physician-referred subjects are actually seeking relief from their psychological symptoms, which they perceive to be related to their poor sleep. In fact, the symptom checklist data described above show that the physician-referred group directly attributes their disturbed mood to their insomnia.
References
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3. Hathaway SR. McKinley JC: Minnesota Multiphasic Personality Inventory. Minneapolis. University ofMinnesota Press. 1943 4. McNair OM. Lorr M. Droppleman LF: ErrS Manual for the Profile of Mood States. San Diego. Educational and Industrial Testing Service. 1971 5. Brodman K. Erdmann AJ. Lorge I. et a1: The Cornell PSYCHOSOMATICS
Stepanski et al.
Medicallndex.JAMA 140:530. 1949 6. RechlSChaffen A. Kales A: A Manual of Standardized Terminology. Techniques and Scoring System for Sleep Stages of Human Subjects. Los Angeles. Brain Informa·
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relation to mood. performance. and nocturnal sleep in chronic insomniacs and noncomplaining sleepers. Sleep 3:230-258.1984 10. Stepanski E. Zorick F. Roehrs T. et aI: Daytime alenness in patients with chronic insomnia compared with asymptomatic control subjects. Sleep I I:54-{)(). 1988 II. Monroe U: Psychological and physiological differences between good and poor sleepers. J Abnorm Psychol 72:255-264.1967 12. Hauri P. Fisher J: Persistent psychophysiologic (learned) insomnia. Sleep 9:38-53. 1986 13. Freedman R. Sattler H: Physiological and psychological factors in sleep-onset insomnia. J Abnorm Psychol 91:380-389.1982
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