The experience of insomnia and daytime and nightime functioning

Psychiatry Research,

12,

235

235-250

Elsevier

The Experience Functioning

of Insomnia

and Daytime

Wallace 6. Mendelson, Debra Garnett, and Herbert Weingartner

J. Christian

and Nighttime

Gillin,

Received December 8, 1983; revised version received April 9. 1984; accepted May 29, 1984, Abstract. Ten insomniacs and matched control subjects, in whom major physiologic disorders such as sleep apnea and nocturnal myoclonus were ruled out, underwent studies of sleep, temperature, motor activity, cognitive performance, and perception of depth of sleep. Subjective descriptions of sleep differed significantly between insomniacs and normals on a variety of variables. In contrast, polysomnographic evaluation showed increased intermittent waking time and decreased sleep efficiency, and only a tendency toward decreased total sleep and increased sleep latency. Minnesota Multiphasic Personality Inventory (MMPI) evaluation revealed that insomniacs had higher scores on the F, D, and SI scales, and lower values on the K scale. On cognitive testing, insomniacs did well on tests of episodic (recent) memory, but displayed major deficits in accessing semantic memory (retrieval of material already known). Compared to normals, insomniacs described rapid eye movement (REM) sleep as relatively “light” sleep. Key Words. Sleep, insomnia, The complaint

of chronic

poor

cognition. sleep is, of course,

very common,

occurring

in perhaps

of sleep research in recent years has been the discovery that insomnia is a complaint that often results from well-described pathophysiological processes such as sleep apnea, nocturnal myoclonus, or circadian dysrhythmias. It is clear, however, that a large group of insomniacs remain in whom major pathophysiologic processes have not been identified, and in whom certain psychological styles related to sleep have been found. In the nosology of the Association of Sleep Disorders Centers (1979) these individuals appear as persistent psychophysiological(A.l.b.), subjective DIMS complaint without objective findings (A.9.b.) and not otherwise specified (A.9.c) complaints. In these groups, relatively little is known about daytime consequences of (or concomitants to) a complaint of chronic poor sleep. There are few data available, for instance, on whether the discomfort of the insomniac at night is translated into impaired performance by day. This is a critical question in assessing the utility of pharmacologic therapy, insofar as many hypnotics may affect daytime function (Mendelson, 1980). up to 10% of the population

(Mendelson,

1980). The major

thrust

Wallace B. Mendelson, M.D., and Debra Garnett, are in the Clinical Psychobiology Branch, National Institute of Mental Health (NIMH). J. Christian Gillin, M.D., is in the Department of Psychiatry, San Diego Veterans Medical Center, La Jolla, CA 92161. Herbert Weingartner. Ph.D., is in the Laboratory of Psychology and Psychopathology, NIMH, Bethesda, MD 20205. (Reprint requests to Dr. W.B. Mendelson, Clinical Psychobiology Branch, NIMH, Bldg. 10. Rm. 4S239,9000 Rockville Pike, Bethesda. MD 20205, USA.) 0165-1781/84/$03.00

@ 1984 Elsevier Science Publishers

B.V

236 Similarly, although there have been several studies of Minnesota Multiphasic Personality Inventory scores in ,insomniacs, and a few (e.g., Marchini et al., 1983) studies of personality qualities in insomniacs, this area is also still greatly in need of clarification. Finally, some classic studies (e.g., Rechtschaffen, 1968) of “poor sleepers” described alterations in temperature at sleep onset, and changes in perception of being asleep, but relatively little work has been done in populations which are now better defined. The present study was designed to provide a comprehensive view of IO insomniacs and matched control subjects in order to examine these questions. The goal was to characterize a number of aspects of these individuals, including polygraphically and subjectively described sleep, daytime sleepiness, motor and cognitive performance, motor activity and temperature during sleep, personality measures, and perception of the experience of sleep. Methods Subjects were nine women and one man, ages 22-44 (mean 35.3 f 7.3) years, and an age- and sex-matched control group, ages 24-44 (mean 35.4 f 6.5) years (Table I). Educational levels of the two groups were comparable, with each having one person with a high school education, six who had attended college, and three with graduate degrees. They were recruited from newspaper ads, and selected on the basis of a history of at least I year of inadequate quantity or quality of sleep. Any subject with evidence of psychiatric or medical illness based on an interview, physical examination, and routine blood tests was excluded. A history suggestive of phase lag syndrome was also considered grounds for exclusion, as were the presence of sleep apnea, nocturnal myoclonus, or other major illnesses as detected on a screening polysomnogram. Subjects then had a multiple sleep latency test (MSLT). The MSLT was performed by polygraphic monitoring of four 20-minute periods of bedtime during the day, and the mean sleep latency was determined. Psychological studies, which included the Minnesota Multiphasic Personality Inventory (MMPI) (Dahlstrom et al., 1972) the Schedule for Affective Disorders and Schizophrenia (SADS) (Endicott and Spitzer, 1978) and the Horne and Ostberg test of morningness and eveningness (Horne and Ostberg, 1976) were also performed. The main body of the study included an adaptation night (night 1) and two studies of polygraphically monitored sleep (nights 2 and 3). Subjects chose their own bedtime (usually 2330-2400h) and were awakened at 0730h. In the morning, subjects filled out a questionnaire on their estimates of sleep latency and other qualities of their previous night’s sleep (Daily Sleep Questionnaire). Starting on the morning of day 3, subjects remained in the laboratory for 24 hours, during which time they filled out a Stanford Sleepiness Scale and, at four times over the day, a Mood Rating Scale, 100 mm line scales of sleepiness, energy, and anxiety, and simple measures of psychomotor performance (see Mendelson et al., 1982). The psychomotor procedures included a pegboard task (performed once with each hand and then both hands), an automated IOsecond finger tapping test (performed for five consecutive tests with each hand), and a letter cancellation task scored for errors of omission, commission, and time. A series of automated procedures, including continuous tracking, visual vigilance, and quantitative Romberg, were later done on these same subjects in another laboratory and are reported separately (Mendelson et al., in press). During the 24-hour period of observation, rectal temperature was monitored by a Solicorder (Ambulatory Monitoring, Inc.), and motor activity was recorded by a wrist actograph. Cognitive tests were performed four times over the course of this same day. On a final study carried out approximately I week later (study night 4). the subjects’ perceptions of whether they were asleep during different sleep stages were investigated. In an experimented design modeled along the same lines as studies by Rechtschaffen (1968) and Coates et al. (1983) subjects were awakened by a loud (80 dB) tone 5 minutes after the “lights out,” IO minutes after the onset of stage 2. 5 minutes after the onset of stage 4 and REM sleep, and during movement time or intermittent waking time. An investigator then entered the room and asked the subject a

Sex

0730

level

3 years college

6

1

1

1

1

0

0

F

B.A.

8

15

0800

0000

No

1

1

2

1

0

0

F

22

Ph.D.

7.5

5

0600

2300

Yes

1

1

1

1

0

0

F

44

M.A.

8

20

0730

0000

Yes

1

1

1

1

0

0

F

36

and 5 = “a very major difficulty.”

B.A.

5.5

10

0600

2300

Yes

1. Scale of 1-5, in which 1 = “not really a problem”

Highest educational obtained

8. How many hours, on the average, do you think you sleep?

60

2300

6. What time do you usually get up in the morning?

7. How long do you think you take to go to sleep (in minutes)?

No

1

5. What time do you usually go to bed?

1

Daytime tiredness?1

4. Do you usually feel refreshed when awakened?

1

Early morning awakening?1

1

3. Trouble going to sleep?1

during the

0

2. For how many years has this occurred?

Awakenings night?1

0

1. How many nights per week, on the average have you been troubled by disturbed sleep?

Questions about habitual sleep (Sleep Habit Questionnaire):

F

Age

37

of subiects

32

A. Controls

Table 1. Characteristics

2 years college

7

3

0630

2330

No

2

2

1

1

0

0

M

42

High school

8

5

0630

2330

Yes

2

1

1

1

0

0

F

41

8

15

0900

2330

Yes

1

1

1

1

0

0

F

34

B.A.

7

7

0630

2200

Yes

1

2

1

1

0

0

F

40

M.S.

7.5

20

0700

0000

Yes

1

1

1

1

0

0

F

25

1.0

0.4

0.4

0.3

0.0

0.0

0.0

B.A.

7.3 f

0.9

18.5 2 17.9

0700 +_ 0.9

2335?

1.2+

1.2+

1.1 f

1.02

0.0 k

0.0 2

6.5

means

35.4 &

Grow

h) “;

238

m

d

2

*

N

I >

8 >

m

z” c.

239

B 0

8

8

[o

(D

m

s:

d

6

5:

U-J ti

Lo

K

ti

240 series of structured questions related to whether he perceived himself to be awake or asleep just before the tone, how long he thought it had been since the previous awakening, whether he had been dreaming, etc. Cognitive testing involved two types of procedures. One type examined components of episodic memory; the other measured access to semantic memory. Episodic memory refers to learning-memory processes that are involved in storing new information and linking that information to the unique context and sequence in which that information was acquired and stored. Semantic memory refers to that memory system which contains knowledge of events, rules, procedures, and concepts, all of which are in very long-term memory and are no longer linked to the unique context in which that information was acquired. It is access to and use of information in long-term memory that determines how one thinks about and encodes

contemporary experience. The distinction between these two types of memory processes is defined in more detail elsewhere (Weingartner et al., 1979). In the episodic memory procedures, a learning task was presented to subjects at each testing occasion (Sitaram et al., 1978). Subjects were read a list of 12 unrelated common English nouns and were required to remember them in order. Learning-memory testing continued for eight trials, or until subjects could remember all of the items in correct order. A prompted recall test procedure was used also to explore aspects of new learning and the consistency with which subjects would remember recently acquired information. Subjects who were read a list of 14 related common nouns were first tested using a free recall procedure. On subsequent learning test trials, subjects were presented only those words “forgotten” on the previous trial (Buschke, 1973; Weingartner et al., 1981). A third episodic memory procedure used during repeated testing of the subjects was a task in which a subject was presented with 18 words all drawn from the same superordinate category (e.g., of vegetables). Six of the words were read once and six were read twice. Subjects were asked to (1) identify when a word was repeated (a measure of vigilance or attention); (2) have free recall of once vs. twice presented words (episodic memory of well-processed and poorly processed words); (3) identify previously presented words from an equal number of similar distractor items (recognition memory). This task is described in greater detail elsewhere (Weingartner et al., 1982). In the semantic memory procedure subjects were presented with category names (e.g., health) and were asked to generate appropriate word responses that were exemplars of that category during a 90-second period. The measures generated from this procedure are highly correlated with those of others that have been used to measure semantic or knowledge memory function (Weingartner et al., 1983).

Results Subject Characteristics. Table 1 describes demographic characteristics of the subjects, as well as their responses to the Sleep Habit Questionnaire. It can be seen that although the basic entrance criterion was only a history of inadequate quantity or quality of sleep, insomniacs differed significantly from controls on a variety of specific questions about their sleep. The SADS revealed no psychiatric diagnoses in 19 of the subjects; a single insomniac had evidence of one minor depressive episode approximately 10 years previously. The Horne-Ostberg scale of “morningness” and “eveningand normals; both groups had ness” showed no difference between insomniacs “intermediate”(mean f SD) scores of 46.4 f 12.7 and 52.7 + 9.35, respectively; i.e., they were neither morning nor evening persons. MMPI data showed that six insomniacs and two controls had scores in the pathological range (70 or above) on at least one scale. Neither insomniacs nor normals had a group mean above 70. The two groups did differ significantly from each other, however, in four areas (Table 2). Insomniacs

241 had higher scores on the F, D, and SI scales, and lower values on the K scale. This might suggest a greater sense of distress, depression and social introversion, and less defensiveness about responses. Table Scale

2. MMPI

scores

on insomniacs

Insomniacs group means (T score)

and controls

Control group means (T score)

t test NS

L

50.1 +

4.7

49.0 + 10.0

F

57.9 2

8.3

49.4 k

3.3

p < 0.004

K

53.4 f

8.9

62.4 +

5.0

p < 0.01

HS

50.1 f

5.2

51.1 ?

6.0

NS

D

62.0 +

9.3

49.0 !I

6.5

p < 0.009

HY

55.2 k

6.9

56.5 I? 5.0

PD

59.3 k

8.7

57.0 k

6.3

NS

MF

45.1 + 14.3

46.6 k

9.1

NS

PA

60.9 2

6.3

56.5 +

5.9

NS

PT

55.8 +

8.2

50.8 k

5.9

NS

SC

55.6 f

8.9

54.2 i

3.5

NS

MA

49.8 + 17.0

51.7?

8.1

NS

SI

56.3 + 11.2

44.7 k

6.2

p < 0.009

NS

Values are mean k SD.

Polysomnograhic Data. Table 3 shows sleep data which represent the mean of nights 2 and 3 combined. It can be seen that insomniacs had nonsignificant trends toward longer sleep latency and shorter total sleep. The only differences reaching statistical significance were an increase in intermittent waking time (p < 0.05) and a decrease in sleep efficiency (p < 0.05) in the insomniacs. Reports of Sleep. Each morning subjects filled out a Daily Sleep Questionnaire containing 18 items regarding their impression of the previous night’s sleep. The striking quality was the lack of differences between the two groups. The only significant contrast was that the insomniacs described less fatigue before going to bed 0, < 0.04), with values of 1.9 f 0.17 compared to 2.4 f 0.17 (on a scale of l-4 in which a value of 1 refers to “not at all tired”). Correlation coefficients were obtained between 21 major polygraphic sleep parameters and items on the self-rating 100 mm line scale, the Mood Rating Scale, performance tasks (finger tap, letter cancellation, pegboard), the Stanford Sleepiness Scale, and the Daily Sleep Questionnaire. For this procedure the insomniacs and controls were analyzed separately. Because of the large number of pairs of measures that were tested (roughly l,lOO), only those with a significance ofp < 0.009 or better were considered in depth. Twenty-three such relationships were found. Interestingly, none of these involved total sleep time or sleep latency, measures which intuitively might be thought to be important to performance and mood the next day. Some associations to intermittent waking time were found, however. Another striking Subjective

242

quality was the lack of similarity between associations of sleep and daytime functioning in insomniacs and normals; i.e., sleep parameters which correlated with mood or performance the next day in insomniacs did not have similar relationships in the controls. Among the correlations which seemed to have some intuitive meaning were: (1) REM latency was positively associated in the insomniac group with a retrospective report of deeper sleep @ < 0.006; Daily Sleep Questionnaire) and a sense of being more awake the next morning @ < 0.0006; Stanford Sleepiness Scale at 6 a.m.); (2) stage 4 time was associated with a report of deeper sleep in insomniacs @ < 0.0006; Daily Sleep Questionnaire); (3) intermittent waking time was positively associated with time to complete the letter cancellation task in insomniacs (p < 0.01); (4) intermittent waking time was positively associated with anxiety the next morning in controls @ < 0.005; Self-Rating Scale); (5) number of awakenings was inversely related to feeling rested in the morning in the normals (p < 0.0003; Daily Sleep Questionnaire). Table 3. Sleep parameters of insomniacs Sleep parameters

and normal controls

Insomniacs (n = 10) Mean SD

Controls (n = 10) Mean SD -

t test

Total sleep 364.70

103.02

389.82

34.55

Sleep latency

46.27

40.08

25.90

11.79

NS NS

REM latency

86.67

40.04

84.45

19.85

NS

94.65

36.18

97.22

17.99

NS

47.87

24.00

25.85

19.04

p < 0.05

467.45

123.77

450.87

36.85

77.60

11.62

86.34

4.36

24.89

4.48

24.92

3.63

NS

1.39

0.43

1.38

0.33

NS

(minutes)

Total REM (minutes) Intermittent

waking

time Total recording time Sleep efficiency REM (O/o) REM density

(%)

NS

p < 0.05

REM index

121.40

71.91

102.70

26.56

NS

Non-REM

270.05

70.69

292.57

28.22

NS

17.45

11.25

11.45

9.95

NS

4.48

2.95

2.86

2.44

NS

Stage 1 (minutes) Stage 1 (%)

195.47

62.17

220.65

33.48

NS

Stage 2 (%)

53.34

7.32

56.29

5.16

NS

Stage 3 (minutes)

21.05

9.64

24.17

10.58

NS

6.16

2.68

6.31

2.73

NS

Stage 4 (minutes)

36.07

21.61

36.30

16.44

NS

Stage 4 (%)

11.08

7.79

9.57

4.27

NS

Delta (minutes)

57.12

18.43

60.45

16.20

NS

(%)

17.26

7.32

15.90

4.22

NS

12.25

13.74

9.30

11.55

NS

Stage 2 (minutes)

Stage 3 (%)

Delta

EMA (minutes)

All values except percentages refer to mean *SD minutes.

243 Daytime Sleepiness and Functioning-Self Assessment. The subjects filled out two types of ratings at four time points over a 24-hour period-a series of 100 mm line scales regarding sleepiness, energy, and anxiety, and a Mood Rating Scale. In contrast to their description of their habitual state, the insomniacs and normals did not significantly differ from each other on any of these measures of how they were feeling at a given moment (Table 4). (In the analysis of variance, there were some significant effects of time of day, indicating circadian aspects of reports of mood from both groups combined.) Similarly, there were no significant differences between the two groups on the Stanford Sleepiness Scale.

Table 4. Self-assessment of daytime mood and function in insomniacs and controls A. Mood-rating scale

p value’

1. Euphoria

0.04 (time effect)

2. Activation

0.001 (time effect)

3

Depression

NS

4. Dysphoria

NS

5. Physical

symptoms

NS

6. Sleepiness

NS

B. Self-rating scale

0.04 (time effect)

1. Reason

clearly

2. Process

information

3. Ability 5. Level

quickly

0.005 (time effect)

to concentrate

0.01 (time effect)

decisions

0.005 (time effect)

4. Accurate

of motor

6. General

p value’

mood

activity state

NS NS

7. Asleep/alert

NS

8. Calm/anxious

NS

9. Tired/energetic

NS

1. Results of two-way ANOVA with one repeated measure, assessing the effect of group and time on ratings.

Daytime Sleepiness-Objective Measures. Multiple sleep latency tests were performed on all subjects. As expected, the control group had a mean sleep latency (to onset of stage 1) of 18.9 f 0.52 minutes (mean + SD), indicating no significant sleepiness. Insomniacs had similar scores of 18.7 + 1.59 minutes, which seem to correspond to their subjective reports, in which they did not differ in sleepiness from controls (Fig. 1).

244 Fig. 1. Multiple

Sleep Latency Test scores in insomniacs

and controls

10 9

1 0 0

13

14

15 SLEEP

16

17

LATENCY

(min)

18

19

20

Daytime Functioning-Psychomotor Testing. Three types of psychomotor tasks were performed four times over the 24-hour study period: a pegboard task, an automated finger tap rate measure (both tasks were done with each hand), and a letter cancellation task. The results were similar in outcome to those of the subjective sleepiness measures: Out of 13 measures among these tasks, there was only one difference (p < 0.0 1) between groups, showing a small decrement in finger tapping rate in the insomniacs using their right hands in the first of five trials. The only other finding was an effect of time of day on one other finger tapping measure (mean rate with right hand). Daytime Functioning-Cognitive Tasks. Measures of attention, vigilance, learning, and memory were not reliably different in insomnia patients and normal controls. This was the case for every component of cognitive processing involved in episodic memory determined from the procedures previously described. For example, the two subject groups differed by less than l/2 standard deviation on measures of list learning of both unrelated words and related words, the recall of once presented items, and memory for stimuli presented from two to seven times (Table 5). In addition, automatic episodic memory functions were also not altered in the insomnia patients; i.e., the ability to monitor how often an event occurred was precisely the same in the insomniacs compared to controls. In contrast to the apparently normal episodic memory functions in the insomnia patients, their ability to access previously acquired knowledge was markedly impaired. At each time of the day that patients were tested, they were far less productive in generating items from long-term semantic or knowledge memory (F= 4.3; df = 1, 34; p < 0.05). The insomnia patients could think of 40% fewer responses

245 associated to stimuli representing categories of knowledge that were familiar and part of their previous experience. This lack of productivity was even more striking in their retrieval of the less common or stereotyped elements that form part of their knowledge structures. Table 5. Access to knowledge in semantic memory in insomnia patients and normal controls (mean f SD) Number of responses generated in 90 seconds Time of day

Normal controls

Insomnia patients

1la.m.

12.9 (f 3.6)

10.4 (k 3.3)

2p.m.

13.8 (+ 2.7)

11.3 (? 3.9)

5p.m.

13.3 ik3.3)

10.6 (t 3.6)

8p.m.

13.9 (k 3.3)

11.3 (k3.3)

F = 4.3; df = 1, 34; p < 0.05

Measures. As can be seen in Fig. 2, core temperature at sleep onset tended to be higher in insomniacs, but did not reach statistical significance, perhaps due to large variability. The time of lowest temperature was approximately the same in the two groups, suggesting no evidence for phase shift. The possibility that any potential temperature differences in insomniacs could be due to more wakefulness after sleep onset seems unlikely; as can be seen in Fig. 2, during the first 2 hours after insomniacs did fall asleep, they had the same or less wakefulness than controls. Correlations between temperature and motor activity during the first 4 hours of sleep in the insomniacs and controls did not reach statistical significance. Temperature

Motor Activity. Wrist actograph data indicated that the insomniacs had a nonsignificant trend toward higher motor activity (3.7 * SD 2.45) units compared to controls (I .4 * SD 0.39) in the first 2 hours of sleep. Cognition During Sleep. As described earlier, subjects were awakened at five electroencephalographically (EEG) defined points over the night; subjects were asked whether they had been asleep just before hearing the tone and other related questions. It was found that the two groups did not differ at any of the time points in their likelihood of reporting being awake or asleep. Of those who described themselves as having been asleep when awakened from REM sleep, however, insomniacs were significantly (p < 0.05) more likely to describe sleep as “light” compared to normals. The two groups did not differ in their descriptions of mental content as being either more “thought-like” or more like imagery. Neither group had significant differences between objective time and estimates of time since the previous awakening. The duration of the 80 dB tone needed to awaken the subjects was also measured. The groups differed only when tones were played during movement time or intermittent wakening time. In that situation a tone of 6.6 + 2.5 (SD) seconds was necessary to

246 induce a response from insomniacs, normals @ < 0.01). Fig. 2. Rectal temperature controls

while only 3.8 f 1.3 (SD) seconds was needed for

and waking time after sleep onset in insomniacs and

98.8 -

98.8 -

Insomniacs

---*

controls

21 19 17 15 -

11 97- 2313

ly

I I1 I \

I / \ J_J ” ‘11

\

5-

\ I I , I I II I I L-q 01234587

,

I I 1 1

01234587 HOURS FROM SLEEP ONSET

Upper: Rectal temperature

in the 7 hours after sleep onset in insomniacs

(left) and normals (right).

Lower: Waking time after sleep onset.

Discussion In summary, carefully screened insomniacs were found to have mildly disturbed sleep, characterized primarily by increased waking time and decreased sleep efficiency by EEG criteria. There was also a tendency toward increased motor activity in the first 2 hours after EEG-defined sleep onset. In contrast, their descriptions of habitual sleep patterns differed markedly from those of controls. MMPI data showed relatively little pathology compared to statistical norms, but did have significant differences

247 compared to the control group. This suggested that insomniacs experience an enhanced sense of distress, depression, and social introversion. Perhaps the most striking quality of the insomniacs’ responses to the various questionnaires was the contrast between the way they pictured their habitual patterns and the way in which they described themselves on a moment-to-moment basis. The insomniacs described themselves as habitually more tired during the day, and as being less refreshed on awakening. With regard to questions of how subjects felt at a given moment in the daytime, however, both the 100 mm scales and the Mood Rating Scales showed no differences in feelings of being tired, sleepy, or degree of activation. At bedtime the insomniacs actually described themselves as less fatigued. A pegboard test and finger tapping test did not show major changes in daytime performance. On the other hand, cognitive testing indicated that although insomniacs did well on episodic memory, they had clear impairment of semantic memory (the ability to retrieve and use material already well known). Core temperature data indicated that the insomniacs had a tendency toward an in-phase elevation of temperature which, at least at sleep onset and the first 2 hours of sleep, could not be explained by increased wakefulness. Arousal studies indicated that, compared to normals, insomniacs are more likely to identify REM sleep as “light” sleep. The polygraphic sleep data presented here-which showed decreased sleep efficiency, an increase in intermittent waking, and a tendency toward less total sleep-are consistent with previous studies. The possibility should be borne in mind that with a larger number of subjects, more subtle differences in sleep (or other measures) between the two groups might emerge. Detailed compilations of such work have been summarized elsewhere (Institute of Medicine, 1979). Representative studies include that of Carskadon et al. (1976), who found decreased sleep time, but also substantial overlap with controls. In that study only one in five patients complaining of a long sleep latency or short sleep time had clear polygraphic confirmation of that problem. Frankel et al. (1976) found that insomniacs slept about 43 minutes less than controls, again with considerable overlap. When correlations were performed between polygraphically defined sleep pa: ameters and daytime mood and performance, several qualities of the data became apparent. The first was the relative lack of relationship between the two. Particularly striking was the absence of a relation to total sleep or sleep latency-measures commonly thought to be important in the cause of (and measures of treatment for) insomnia and its presumed daytime consequences. There was some evidence that intermittent waking time may be more related to daytime mood and performance, suggesting that it is the continuity, rather than total amount of sleep,that is important. It should be emphasized that these relationships were taken from a very large number of possible correlations. In order to confirm the meaningfulness of these relationships, it will be necessary to use them for predicting correlations in future studies. In this study there was a small tendency toward increased motor activity early in sleep. Thoresen et al. (198 1) found no differences in motor activity between controls and patients with either sleep onset or sleep maintenance problems, but did find higher activity scores in insomniacs with combined problems. Interestingly, they found no difference in daytime activity scores of insomniacs and normals, an observation germane to the daytime performance studies presented here.

248 This study found that although insomniacs as a group did not suffer significantly from normative data on the MMPI, significant contrasts with matched controls were found. A number of previous studies have also examined personality traits in insomniacs. In studies from Los Angeles and Hershey, PA., 80-85% of insomniacs had an elevated score on at least one scale (Kales et al., 1976) compared to 60% in the current study. Most earlier studies tended to find highest scores on the depression, hysteria, and psychasthenia scales. The present study found insomniacs rating higher on the depression scale. Others have shown significant elevations across a broad range of seven scales (Kales et al., 1978). Monroe (1967) found poor sleepers to have lower scores on the K scale as did the current study, suggesting perhaps less defensiveness about responses. Roth et al. (1976) also found an elevation of the “neurotic triad” scales for depression, hypochondriasis, and hysteria. Work with other instruments such as the Marchini Monitoring Inventory has also suggested that insomniacs differ from controls in some personality traits, including preoccupation with self (Marchini et al., 1983) a result consistent with the high scores reported here on the social introversion scale. Thus, both clinical impression and formal testing continue to indicate that insomniacs differ in some personality qualities, which are still in need of more adequate description. An objective measure of daytime sleepiness (Multiple Sleep Latency Test; MSLT) indicated no general tendency toward sleepiness in insomniacs. Values were approximately the same as controls, and only one patient out of 10 could be said to have any evidence of sleepiness. This seems to confirm the MSLT study of Dement et al. (1982) in which the single most common value for insomniacs was 20 minutes. Whatever daytime distress is experienced by insomniacs is apparently not manifest as objective sleepiness. Insomniacs did not show deficits with the relatively simple motor tests reported here. There is little information in the literature on this subject. Linnoila et al. (1980) studied patients selected on the basis of history but without polysomnography. Using a sophisticated automated battery of measures, they reported that insomniacs had greater variability in performance over time, and decrements in tracking and reaction time. Thus, the question of daytime psychomotor deficits in insomniacs continues to need further clarification. Cognitive testing results showed a very clear deficit in a specific aspect of memory processes-semantic memory, or the ability to retrieve well-learned information that is part of one’s knowledge base. Thus, although these patients can easily learn new information, they are less able to use what they already know. In addition, they may demonstrate impairment in manipulating and organizing information. Subjectively, this may be experienced as an inability to think in a clear, crisp fashion. Whether the deficit is a result of, or contributor to, their distress is not clear. The type of cognitive deficit described here, however, may be reflected in their inconsistent views of themselves. That is, they experienced a marked contrast between their characterization of their habitual state, which was distressed, and their perception of how they felt at any given moment, which was relatively normal. Rechtschaffen (1969) reported that when an investigator entered the room of a poor sleeper 10 minutes after the first sleep spindle, 6 of 22 described themselves as being

249 awake, while this occurred with only one good sleeper. Similarly, Coates et al. (1983) reported that poor sleepers were more likely to describe themselves as awake at the time of the first sleep spindle and 10 minutes after the second spindle. In the present study this general technique was used at five points across the night. Unlike the previous studies, the two groups did not differ in the likelihood of describing themselves as being awake. On the other hand, insomniacs did perceive themselves to be in “lighter” sleep during REM sleep. Thus, there continues to be some evidence that insomniacs perceive the experience of sleeping differently than normals in a given polygraphically defined sleep stage. In the present study it was also found that during movement time or intermittent waking time it took almost twice the duration of a loud tone to cause an insomniac to acknowledge that he was awake compared to normals. Coursey et al. (1975) presented evidence that insomniacs were less reactive to external stimulation, a notion compatible with these results. One might speculate that insomniacs are more absorbed with internal processes such as ruminations. Monroe (1967) reported that poor sleepers differed from good sleepers immediately before and during sleep on a variety of autonomic measures, including temperature, heart rate, pulse volume, and vasoconstriction rate. Although most of these observations were consistent with the concept of heightened autonomic activity in poor sleepers, the higher skin resistance (usually a sign of relaxation) in the poor sleepers suggests that the issue is more complex (Rechtschaffen, 1969). In the present study there was a trend toward an increased temperature during the first 2 hours of sleep, which (during that period, at least) was not due to increased wakefulness. This was similar to Monroe’s (1967) finding of a mean temperature increase of 0.34OF in “poor sleepers” at sleep onset. It is possible that this sign of physiological activation corresponds to the seemingly puzzling finding that at bedtime insomniacs reported being less tired on the Daily Sleep Questionnaire. In summary, insomniacs differ from normals in polygraphically defined sleep, perception of their habitual but not immediate condition, subjective level of arousal during sleep, and cognitive function when awake. References Association

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