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Sleep, 4(1):39-47
© 1981 Raven Press, New York
Differentiating Psychological Characteristics
of Patients with Sleep Apnea
and Narcolepsy
*Larry E. Beutler, tJ. Catesby Ware, tIsmet Karacan, and
tJohn 1. Thornby
*University of Arizona College of Medicine, Tucson, Arizona; tSleep Disorders
Center, Department of Psychiatry, Baylor College of Medicine, and Sleep Laboratory,
Veterans Administration Hospital, Houston, Texas
Summary: Fifty male subjects were group-matched for age and socioeconomic status. Twenty of the subjects were diagnosed as having sleep apnea
and 20 were diagnosed as having narcolepsy on the basis of sleep studies.
The remaining 10 subjects served as normal controls. Differences among
the groups were evaluated on the bases of two psychological instruments
designed to assess personality characteristics and mood states. The find-
ings suggest that narcoleptics and apneics both present discriminatively
different psychological profiles than do normals. Moreover, personality characteristics of these two groups are distinguishable from one another. Apneics
tend to be individuals with hypochondriacal and hysterical characteristics,
whereas narcoleptics are more easily characterized by anxiety and social introversion. Both severity of psychological disturbance (mean Minnesota' Multiphasic Personality Inventory elevations) and personality pattern (two-point
codes) distinguish the groups. Key Words: Sleep apnea-N arcolepsyPsychological profiles.
There have been few investigations of the personality characteristics associated
with those sleep disorders which apparently have an organic etiology. In contrast,
functional sleep disturbances such as initial insomnia have frequently been attributed to the personality characteristics and coping styles of the sufferers (e.g.,
Monroe, 1967; Kales et aI., 1976). This lack of data is becoming increasingly
apparent as more and more research suggests that life stress, psychological coping
styles, and other characteristics of personality may strongly influence the onset
and course of a wide variety of clearly organic diseases (e ,g., Holmes and Rahe,
1967; Kimball, 1972; Roessler, 1976). Current conceptualizations of the relationship betwen psychological and somatic variables suggest that any physical disease
Accepted for publication November 1980.
Address correspondence and reprint requests to Dr. Beutler at Department of Psychiatry, Arizona
Health Sciences Center, Tucson, Arizona 85724.
39
40
L. E. BEUTLER ET AL.
process represents the final common pathway of a number of influences, including
sociocultural ones and those related to a patient's ability to cope with stress.
The limited survey and clinical information that is available suggests that there
may be certain personality characteristics associated with physiological sleep disorders. For example, Broughton and Ghanem (1976) observe that narcoleptics
may have difficulties with issues of autonomy and the establishment of independence. They observed that narcoleptics are prone to mood changes, depressive
episodes, and are generally worrisome individuals. Sleep apnea patients, the other
large patient group that commonly presents with excessive daytime sleepiness,
often manifest irritability, anxiety, poor concentration, and symptoms of depression (Okada et aI., 1977; Guilleminault et aI., 1978; Neil et aI., 1978). These
findings suggest that there may be psychological manifestations which are peculiar
and particular to the conditions of narcolepsy and sleep apnea. This paper represents an effort to investigate the personality and mood characteristics of these
patients.
METHOD
Subjects
Fifty male subjects comprised the sample for this study. Twenty of these males
were diagnosed as having obstructive sleep apnea on the basis of complaints and
diagnostic sleep studies. Final diagnosis was based on 3 nights oflaboratory study
in which electroencephalogram - electro-oculogram (EEG - EOG) monitoring was
performed along with measurements of nasal-oral respiration, oxygen saturation,
esophageal pressure, and heart rate. All apnea patients satisfied the minimum
diagnostic criteria of 50 apnea episodes of at least 10 sec duration during each
night of the evaluation. An additional 20 subjects were diagnosed as having narcolepsy on the basis of clinical history and diagnostic sleep studies. The final
diagnosis of this group was based on a minimum of 3 nights of laboratory study
during which EEG-EOG, respiration, and heart rate variables were recorded.
Both rapid eye movement sleep latency of less than 15 min for at least 1 night and
two symptoms from the classical narcoleptic tetrad were required for a final
diagnostic classification. In the latter part of the study, diagnoses were also confirmed with multiple sleep latency tests (Richardson et aI., 1978) and measures of
regional cerebral blood flow (Sakai et aI., 1979). These studies were performed
after withdrawal of all current medications.
The control group consisted of 10 individuals who presented no sleep disorder,
medical complaint, or symptoms. These subjects were recruited through advertisements and had no sleep complaint or known medical condition. They were
studied through a similar three-session series of laboratory nights, during which
EEG-EOG recordings, respiratory function, and other measurements were obtained. Control subjects were retained for study only if these findings were within
normal limits.
Subjects in all three groups were given a general physical and psychiatric
examination. Those with primary medical or psychiatric disorders were ruled out
Sleep, Vol. 4, No. I, 1981
DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS
41
for further study. Patients were recruited through advertisements in newspapers
or were referred by their physicians. All subjects were selected in order to insure a
group match on the basis of education and age. Consecutively admitted patients
and volunteers who met the requisite criteria for one of the groups were selected
for study. Ages and socioeconomic status of the three groups were not significantly different. Mean ages were 45.6 years (SD = 6.8) in the apnea group, 42.3
years (SD = 11.2) in the narcolepsy group, and 41.7 years (SD = 7.7) in the control
group. Mean educational levels in the three groups were 14.3, 14.0, and 13.75
years, respectively.
Procedure
All subjects were admitted to the Baylor College of Medicine Sleep Disorders
and Research Center and were administered psychological tests in a routine fashion. Standard polysomnographic procedures were used in wiring, recording, and
scoring of sleep data (Williams et aI., 1974). The psychological measures consisted
of the Minnesota Multiphasic Personality Inventory (MMPI) and the Profile of
Mood States (POMS). The MMPI was scored on both the validity and the 10
clinical scales. Scores on this test were assumed to reflect relatively stable personality characteristics and predispositions. In contrast, the POMS was assumed
to evaluate a patient's transitory moods and general affects. This latter test
evaluates six areas of state-related mood functioning; tension, depression, anger,
vigor, fatigue, and confusion.
One-way analyses of variance with a two-tailed alpha criteria were initially used
to compare the three groups on each of the 13 MMPI scales and 6 POMS scales.
When any of these was significant, we then compared the groups two-at-a-time
using the Scheffe multiple comparison procedure (Scheffe, 1959) in order to establish the source of the differences. A stepwise discriminant analysis (Dixon,
1979) was also performed to determine the combination of scales from the MMPI
and POMS that optimally distinguished among the three groups.
In addition, the high-point codes (i.e., peak scores independent of actual elevation) from the MMPI were extracted for each subject and a tabulation was made of
the frequency with which each of the MMPI scales fell within this high-point-code
profile for each group. The two most frequent scales for each group were extracted and formed the basis for developing a two-point rule for distinguishing
among the three groups. Each subject was scored as having the particular profile if
either one or both of the two characteristics were reflected in the subject's highest
two scores. The three MMPI profiles (one for each group) were then separately
analyzed in all pairwise comparisons between the three groups in a series of 2 x 2
X2 analyses (i.e., each combination of groups was separately compared on each
code type). It should be noted that unlike the other analyses, this analysis reflected differences in pattern rather than symptom intensity.
RESULTS
All relevant statistical comparisons relied on two-tailed tests of significance.
Sleep, Vol. 4, No.1, 1981
L. E. BEUTLER ET AL.
42
Individual Scale Comparisons
Mean values for the three groups of subjects on the individual MMPI and POMS
scales are illustrated in Table 1. Differences among means are illustrated in Figs. 1
and 2. Narcoleptics were distinguished from controls as being relatively more
depressed, anxious, and fatigued and as having less vigor. Apneic patients were
distinguished from controls as being relatively more hypochondriacal (Hs) and
depressed, and as being less vigorous. When comparing the two patient groups,
we found that narcoleptics were relatively more socially introverted and confused
than apneics, whereas apneics expressed relatively greater denial than narcoleptics.
When considering the combined patient groups in comparison to the controls, it
is apparent that the best individual discriminators are vigor, depression,
hypochondriasis, fatigue, and psychasthenia. All these scales indicate values in
the direction of impairment for the patient groups.
Discriminant Analysis
A multiple discriminant analysis was performed and was designed to determine
which of the POMS and MMPI scales best distinguished among the three groups.
TABLE 1. Means and standard deviations of personality scales
Scales
MMPI
Hs
D
Hy
Pd
Mf
Pa
Pt
Sc
Ma
Si
L
F
K
POMS
T
D
A
V
F
C
Control
Narcoleptic
Apneic
49.00
49.60
53.40
53.10
61.80
51.60
47.00
51.20
55.70
46.40
47.50
51.00
57.50
(4.37)
(7.24)
(4.64)
(10.52)
(6.81)
(8.30)
(7.44)
(9.65)
(10.62)
(9.58)
(3.83)
(4.52)
(7.36)
57.75
61.35
59.20
57.29
63.45
53.35
59.75
59.30
59.00
56.75
46.90
55.45
52.05
(10.06)
(12.47)
(8.60)
(7.54)
(11.00)
(9.19)
(11.84)
(10.45)
(9.94)
(10.49)
(5.49)
(6.98)
(9.41)
62.05
60.54
61.90
60.00
59.60
51.05
54.65
52.75
54.75
47.50
50.05
51.56
59.60
(10.21)
(10.72)
(10.36)
(11.87)
(9.58)
(8.60)
(11.07)
(9.50)
(9.37)
(8.69)
(7.43)
(4.33)
(7.67)
6.70
4.70
4.90
22.60
3.50
3.70
(3.88)
(5.27)
(4.12)
(4.29)
(3.80)
(2.86)
9.45
9.60
7.25
14.40
10.75
7.65
(6.37)
(11.70)
(7.45)
(5.56)
(6.12)
(5.36)
7.90
4.85
4.75
13.70
8.00
4.15
(7.14)
(8.80)
(7.19)
(4.75)
(5.25)
(3.59)
Abbreviations used in the scales: Minnesota Multiphasic Personality
Index (MMPI): Hs, hypochondriasis; D, depression; Hy, hysteria; Pd,
psychopathic deviant; Mf, masculinity-femininity; Pa, paranoia; Pt,
psychasthenia; Sc, schizophrenia; Ma, hypomania; Si, social introversion; L, F, and K are validity scales suggesting various denial patterns
and deviant response sets. Profile of Mood States (POMS): T, tension;
D, depression; A, anger; V, vigor; P, fatigue; C, confusion.
Sleep, Vol. 4, No.1, 1981
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DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS
43
Controls
Narcoleptlcs
, Apnelcs
1
1
60
t
*
*
55
50
45
40
o
Hs
Pd
Hy
Mf
Pa
Pt
Sc
Ma
51
L
F
K
MMPI SCALES
FIG. 1. Mean MMPI scale scores for controls, narcoleptics, and apneics. Asterisks indicate the level
of statistical significance of comparisons between the indexed patient group and matched controls (*, p
< 0.05; **, p < 0.01; ***, p < 0.001). A cross indicates a statistically significant (p < 0.05) difference
between the two patient groups (apneics vs. narcoleptics). See Table I for the abbreviations used.
20
15
10
5
o
T
o
A
v
F
c
POMSSCALES
FIG. 2. Mean POMS scores for controls, narcoleptics, and apneics. See Fig. I for the meaning of
the symbols and Table 1 for the abbreviations used.
Sleep, Vol. 4, No. I, 1981
L. E. BEUTLER ET AL.
44
The stepwise analysis allowed all discriminating (p < 0.05) variables to be
weighted according to their discriminative po\ver. The analysis was terminated at
the point where the F to remove value ceased to be significant at the 0.05 level for
all variables in the equation.
Two scales [social introversion (Si) and vigor (V)] entered the stepwise discriminate function analysis as significant discriminators among the three groups.
None ofthe remaining scales added significant improvement to the model. Table 2
summarizes the results for these two variables in discriminating between each pair
of groups. From the right-most column of the table, it is evident that the model
more easily distinguishes between controls and patients than between the two
groups of patients. The bottom row shows that the POMS vigor scale is a more
powerful discriminator than the MMPI social introversion scale. An interpretation
of the model can be illustrated by the linear discriminant function comparing
controls and narcoleptics:
I = 0.0757 Si - 0.2912 V + 1.4818
If I > 0, classify as narcoleptic
If I < 0, classify as control
Thus we see that a low vigor score and a high social introversion score would
characterize a narcoleptic patient in contrast to a control.
The classification matrix for the above model is shown in Table 3. The control
subjects were quite readily distinguished from either patient group (i.e., a high
specificity for the model) by elevations in these two scales. Apneic patients were
quite distinguishable from controls and narcoleptics, but narcoleptic patients were
only moderately distinguishable from other groups using this model (i.e., only fair
sensitivity) .
High-Point Pattern Analysis
Results of the high-point pattern analyses are summarized in Table 4. It should
be underlined that these analyses address a very different question than the previous two analyses. Namely, the two-point code analyses are performed without
regard for actual scale elevations, but rather focuses on the most frequent scale
patterns. In other words, the previous comparisons reflect intensity of disturbance
as distinguishing characteristics, whereas pattern analysis addresses the type of
characteristics which distinguish the groups. This analysis also differs from
TABLE 2. Pairwise discrimination
Coefficients of model
Comparison groups
Si
V
Const
Assigned group
if value >0
Controls vs. narcoleptics
Controls vs. apneics
Narcoleptics vs. apneics
+.0757
-.0337
-.1095
-.2912
-.3688
-.0776
+ 1.4818
+8.2782
+6.7964
Narcoleptic
Apneic
Apneic
5.27"
1O.70 b
F to Remove of each scale
a
b
Statistically significant at the p < 0.01 level.
Statistically significant at the p < 0.001 level.
Sleep. Vol. 4. No. /. /98/
F value
of model
1O.35 b
1O.59 b
5.22"
DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS
45
TABLE 3. Classification matrix
Assigned group
Actual group
Control
Narcoleptic
Apneic
9
5
1
9
3
2
0
6
15
Control
Narcoleptic
Apneic
Percent
correct
90
45
75
discriminant analysis in that it initially focuses on each scale among groups.
Thus, the high two-point profile for one group may distinguish it from another
group even though the mean evaluations for the two scales in the profiles may
be similar in both groups. What makes the two scales unique for one group is
that their scores are high relative to those of the other scales in their own group.
Because cell frequencies for the X2 analyses are small, the results must be
interpreted with caution. Usually an expected cell frequency of 5 is considered
necessary for reliable results. In a few instances, the results were based on an
expected cell frequency of slightly less than 4. However, in view of the demonstration (Knetz, 1963) that expected cell frequencies as low as 2.5 still produce
reliable results, we elected to proceed with the analyses.
In all comparisons (Table 4) the two scales that characterized the MMPI profiles
of each group significantly differentiated that group from each of the others, but
did not distinguish between the other two groups. The control group was characterized either by having high femininity or manic scores relative to the other
scores. Similarly, the narcoleptics were characterized as having either high anxiety or social introversion scores compared to their other scores, and the apneics
as having relatively high hypochondriasis or hysteria scores.
DISCUSSION
The current findings support the general hypotheses that both the intensity of
psychological symptoms and the dominant personality patterns of male apnea and
narcoleptic patients distinguish them from one another and from normal controls.
TABLE 4. Frequencies of two-paint-code patterns
and X 2 results
MMPI scale
Group
Controls (C)
Narcoleptic (N)
Apneic (A)
CxN
CxA
NxA
Mfor Ma
8
10
8
Pt or Si
I
10
2
6.67 b
4.59"
4.71"
0.00
0.40
7.62b
Hs or Hy
1
6
14
1.47
9.60 b
6.64"
a p < 0.05.
b P < 0.01.
See Table I for abbreviations.
Sleep, Vol. 4, No. I, 1981
46
L. E. BEUTLER ET AL.
At least within a male population, it is interesting to observe that the intensity of
psychological symptoms, as well as the dominant personality pattern, success",
fully distinguishes between collapsed groups of patients and normals. Distinctions
between apnea and narcoleptic patients are more difficult to make on the basis of
symptom intensity, however. Only in relative levels of social inhibition does the
intensity of symptom differentiate between male apnea and male narcoleptic patients. While both tend to suffer from lack of vigor ,compared to normals, the male
sleep apnea patient is considerably less likely to become socially introverted in
coping with the difficulty.
As indicated, the intensity of psychological symptoms is most consistent in
differentiating collapsed groups of apnea and narcolepsy patients from normal
controls. However, the dominant personality patterns present in these groups,
irrespective of symptom intensity, seem to distinguish the two patient groups
quite reliably. Analysis of these dominant personality features (pattern analysis)
suggests that narcoleptics are most often characterized by personality patterns
which. emphasize coping with stress by sensitization to sources of anxiety and
social withdrawal than are the other groups. In contrast, the personality styles of
control subjects tend to be characterized by relative reliance on nonaggressive but
externalized anxiety (dominant Ma and Mf MMPI patterns). These findings are
consistent with the speculations of Broughton and Ghanem (1976), who suggest
that narcoleptics may be more anxious and emotionally changeable than normals.
Similarly, apnea patients appear to be more prone than normals to feel deficient
in vigor. Again, as might be expected from their clinical condition, the pattern
analysis suggests that their personality styles are more often oriented toward their
physical well-being, dependency on external events, and physical symptoms than
those of normals.
'
The distinctions between apnea and narcoleptic patients are of particular interest since in the Sleep Disorders Center we often see apnea patients who have been
misdiagnosed as narcoleptic prior to polysomnographic evaluation. The current
findings suggest the presence of dependency needs which dominate other characteristics among the personalities of apnea patients, in contrast to those of narcoleptics. Apparently, apnea patients (at least males) tend to rely on denial and
somatization as opposed to the narcoleptics' reliance on obsessiform and social
distancing defenses. This latter pattern of emotional and social withdrawal among
narcoleptics can perhaps be explained by their need to avoid situations in which
cataplexy is likely to occur with embarrassing results. Nonetheless, both the
hysteroid and somatizing personality traits of the apnea patient and the social
distancing and obsessiform traits of the narcoleptic stand in some contrast to
normal, matched males who appear to be more frequently characterized by a
physically active but philosophical approach to problems.
While the 3 groups studied here may be differentiated from one another by the
intensity of various psychological symptoms, the relative dominance of certain
personality patterns within patient groups might more directly suggest the presence of a predisposing character type.
More specifically, while the intensity of the narcoleptic patient's social withdrawal and lack of vigor might be a reflection of a reaction to the sleep disturbance itself, the relevant prevalence of hystrionic defenses among apnea patients
Sleep, Vol. 4, No.1, 1981
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DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS
47
and obsessiform-introverted defenses among narcoleptics indicates contrasting
defensive styles which either predispose or arise from the particular sleep disorder. The current data cannot directly provide information on whether the distinctions are a psychological consequence of the disorder or are predispositions to
such disturbance. An ideal, but difficult, approach to this question would be to
follow the development of sleep apnea and narcolepsy longitudinally. For example, one might study the children of patients who have these disorders. Another
approach would be to reevaluate patients after successful treatment in order to
determine if and how their dominant personality patterns might have changed. In
any case, more precise determination of whether these and other personality
characteristics represent preexisting attributes or consequences of a patient's
medical condition is required in future research. While the current data indicate
directions that may be of some significance, increasingly reliable and focused
assessment tools designed to evaluate specific personality (i.e., introversion) and
psychological symptom intensity might be ..employed to some value in further
research efforts.
Finally, the current data underline the interrelationships of psychological and
physical disease processes. The data suggest that the question of treatment among
both apneics and narcoleptics should be considered with reference to the personality characteristics and possible psychological dynamics that contribute to the
patient's problems.
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