Journal of Psychosomatic Res
Psychological and health-related quality of life factors associated with
insomnia in a population-based sampleB
Melanie LeBlanca,b, Simon Beaulieu-Bonneaua,b, Chantal Merettec,d,
Josee Savarda,e, Hans Iversb, Charles M. Morina,b,4
aEcole de psychologie, Universite Laval, Quebec, CanadabCentre d’etude des troubles du sommeil, Centre de recherche Universite Laval-Robert-Giffard, Quebec, Canada
cCentre de Recherche Universite Laval-Robert-Giffard, Quebec, CanadadDepartement de Psychiatrie, Universite Laval, Quebec, Canada
eCentre de recherche en cancerologie de l’Universite Laval, l’Hotel-Dieu de Quebec, Quebec, Canada
Received 13 June 2006
Abstract
Objective: This study examined the relationship of psycho-
logical and health-related quality of life variables to insomnia in
a population-based sample. Methods: Data were derived from a
longitudinal epidemiological study assessing the natural history
of insomnia. The present results are based on the first of four
postal evaluations conducted over a 2-year period. Participants
(n=953) completed questionnaires assessing sleep, psychological
and personality variables, and health-related factors. Participants
were categorized into three sleep status subgroups using an
algorithm based on Diagnostic and Statistical Manual of Mental
Disorders, Fourth Edition, Text Revision and International
Classification of Diseases, 10th Edition diagnostic criteria for
insomnia: (1) insomnia syndrome (n=147), (2) insomnia symp-
toms (n=308), and (3) good sleepers (n=493). Results: Compared
to individuals with insomnia symptoms and good sleepers,
individuals with insomnia syndrome presented lower quality of
0022-3999/07/$ – see front matter D 2007 Elsevier Inc. All rights reserved.
doi:10.1016/j.jpsychores.2007.03.004
B This research was supported by a Canadian Institute of Health
Research grant (#42504).
4 Corresponding author. Ecole de psychologie, Universite Laval,
Quebec, Canada G1K 7P4. Tel.: +1 418 656 2131x3275; fax: +1 418
656 5152.
E-mail address: [email protected] (C.M. Morin).
life and higher scores on measures of depression, anxiety,
neuroticism, extraversion, arousal predisposition, stress percep-
tion, and emotion-oriented coping. The same pattern was observed
for individuals with insomnia symptoms in comparison with good
sleepers. An ordinal logistic regression analysis showed that the
presence of a past episode of insomnia, higher depressive
symptoms, and lower scores on the 12-item Short Form Health
Survey vitality and role physical subscales were the most useful
variables to predict subgroups membership. Conclusion: The
findings indicate that insomnia is associated with increased
psychological symptomatology and perceived stress, higher
predisposition to arousal, and more impairment of health quality.
Longitudinal follow-ups are now being conducted to assess the
relative contribution of those variables in the development and
natural course of insomnia.
D 2007 Elsevier Inc. All rights reserved.
Keywords: Associated factors; Correlates; Epidemiology; Insomnia; Sleep
Introduction
Several epidemiological studies have been conducted to
document the prevalence and correlates of insomnia. An
estimated 30% of the adult population presents insomnia
symptoms, and about 5–10% are affected by an insomnia
syndrome [1–3]. Epidemiological studies have also
demonstrated that prevalence rates increase with age and
are higher among women, the unemployed, unmarried, and
those with lower socioeconomic status [1,4–9]. In addition
to sociodemographics, higher levels of depressive and
anxiety symptoms have consistently been associated with
insomnia [10]. Individuals with insomnia also report
more medical problems (e.g., arthritis, vascular disease),
earch 63 (2007) 157–166
M. LeBlanc et al. / Journal of Psychosomatic Research 63 (2007) 157–166158
an increased use of medications, drugs, and alcohol and
more frequent personal history of insomnia compared to
good sleepers [6,10–15].
Most epidemiological studies examining insomnia corre-
lates have restricted their investigation to depression,
anxiety, and specific health problems [1,4–15]. To our
knowledge, none has explored other variables (e.g., person-
ality, arousability) that may be involved in the etiology of
insomnia in the general population. For instance, in clinical
samples, the personality patterns of individuals with
insomnia have been characterized by the presence of
neurotic traits, inhibition of emotions, rumination, and
inability to discharge anger outwardly [16–20]. Individuals
with insomnia have also been described as having fewer
adaptive coping skills, relying more on emotion-oriented
coping strategies than problem-solving strategies, and
reporting lower feelings of mastery [21–23]. A higher
arousability (i.e., physiological, cognitive, and emotional)
during the day, at bedtime and at night has also been
associated with insomnia [22–25]. Studies have shown that
individuals with insomnia are more emotionally reactive,
more alert and vigilant, and experience more intrusive
thoughts than good sleepers [21,26–28]. Besides psycho-
logical factors, reduced quality of life has been associated
with insomnia in population-based samples [29,30]. Finally,
individuals with insomnia tend to report higher rates of
family history of insomnia than good sleepers [31–33]. With
the exception of one study on quality of life [29], results
from clinical samples have never been replicated to the
general population.
Studies of insomnia correlates have generally considered
single factors separately. Examining several factors simul-
taneously in the same sample can provide a more precise
and exhaustive description of the profile of individuals with
insomnia compared to that of good sleepers. Moreover,
most studies that documented correlates of insomnia have
relied on treatment-seeking individuals recruited from sleep
clinics. Such studies, while valuable, are restricted to
describing a single group of individuals with chronic
insomnia [16,17,31], or when a comparative group of good
sleepers is included, it is typically based on a convenience
sample not drawn from the same population [18,20–22]. In
addition, there has been no systematic investigation of the
characteristics (e.g., personality, depression, and anxiety
symptoms) of individuals with insomnia symptoms only
(i.e., who do not fulfill all the diagnostic criteria of
insomnia, although they represent approximately 30% of
the general population) [1,2]. Consequently, the relation-
ship between insomnia correlates and less severe or
transient insomnia remains unknown. For instance, it is
not known whether the higher levels of depressive and
anxiety symptoms usually observed in individuals with an
insomnia syndrome are also noticeable in individuals with
insomnia symptoms. The investigation of these factors in
individuals with less severe insomnia could guide the
development of effective early intervention programs to
prevent the development of chronic insomnia and subse-
quent mental health disorders.
The objective of the present study was to examine the
relationship between insomnia and psychological and health-
related quality of life factors in a population-based sample,
through a comparison of subgroups of individuals with
insomnia symptoms, insomnia syndrome, and good sleepers.
Methods
Study context and sample selection
Data from this study are derived from a larger
epidemiological study conducted in the province of
Quebec, Canada. The study began with a telephone
survey, carried out by a professional pool firm [1]. The
sample consisted of French-speaking residents of the
province of Quebec, 18 years and older. Sample selection
involved two procedures: (1) random digit dialing method,
which generates geographically stratified phone numbers,
and (2) the Kish method [34], to identify the individual to
be interviewed in each household. These methods ensure
that the sample is representative of the target population.
At the conclusion of the telephone interview, participants
were asked if they wanted to take part in the longitudinal
phase of the study, which involved completion of four
postal evaluations over a 24-month period. The first
evaluation was conducted 1 month after the telephone
interview. The remaining three postal evaluations were
conducted, respectively, 6, 12, and 24 months after the
first evaluation. Data from the first postal evaluation only
are reported in the present study.
Participants and procedure
Of the 5991 persons solicited, a total of 2001 (33.4%)
respondents completed the telephone interview, and 1467
(73.3%) of them accepted to take part in the longitudinal
study. Of this number, 105 were excluded because they
reported the presence of a sleep disorder other than insomnia,
the only exclusion criterion of the study. The first postal
evaluation was mailed to 1362 participants, who were asked
to return the completed questionnaire within a 2-week period.
Reminder telephone calls were made afterwards for those
who had not yet returned the measures. Response rate was
73.2%, with 997 participants having returned the completed
measures for which they received a $25 monetary compen-
sation. Of those, 44 additional participants were excluded
because they reported the presence of another sleep disorder
on the questionnaire, which was not reported at the telephone
interview. The final sample included 953 participants.
Sleep status groups
Participants were classified in three groups according to
an algorithm based on a combination of insomnia diagnostic
M. LeBlanc et al. / Journal of Psychosomatic Research 63 (2007) 157–166 159
criteria from the Diagnostic and Statistical Manual of
Mental Disorders, Fourth Edition, Text Revision (DSM-IV-
TR) [35], the International Classification of Diseases, 10th
Edition (ICD-10) [36], and on the utilization of sleep-
promoting products (prescribed and over-the-counter).
Responses from the Insomnia Severity Index (ISI) [37]
and the Pittsburgh Sleep Quality Index (PSQI) [38] and
from questions on sleep-promoting medication use were
used to evaluate the presence or absence of each criterion.
The three sleep status groups were defined as follows:
! Insomnia syndrome. Participants in this group met all
the diagnostic criteria for insomnia. They were
dissatisfied with their sleep [i.e., dissatisfied (3) or
very dissatisfied (4) on a 0–4 scale] and presented
symptoms of initial, maintenance, or late insomnia at
least three nights per week for a minimum duration
of 1 month. Psychological distress or daytime impair-
ment related to sleep difficulties was also reported
by those individuals [i.e., much (3) or very much
(4) on 0–4 scales]. Finally, if prescribed medication
was used as a sleep-promoting agent at least three
nights per week, participants were automatically
classified in the insomnia syndrome group whether
or not they presented symptoms of initial, mainte-
nance or late insomnia.
! Insomnia symptoms. Participants classified in this
group presented symptoms of initial, maintenance or
late insomnia at least three nights per week, without
fulfilling all the diagnostic criteria of an insomnia
syndrome (i.e., they could be satisfied with their
sleep, not report distress or daytime consequences, or
their sleep difficulties could last for b1 month). Also
included in this group were individuals dissatisfied
with their sleep quality but without symptoms of
initial, maintenance or late insomnia. Lastly, partic-
ipants using prescribed medication to promote sleep
less than three nights per week or over-the-counter
medication at least one night per week were automati-
cally classified in this group.
! Good sleepers. These participants were satisfied with
their sleep [i.e., very satisfied (0), satisfied (1), or
neutral (2) on a 0–4 scale], did not report symptoms
of initial, maintenance, or late insomnia and did not
use prescribed or over-the-counter medication as a
sleep-promoting agent.
Measures
Several measures were used for the purpose of the
present study. These included French–Canadian versions of
validated self-report measures, as well as questions devel-
oped specifically for this study, covering four general
domains: sleep, physical health and health-care service
utilization, coping and life events, and mood and person-
ality. Two sleep questionnaires (ISI and PSQI) [37,38] were
used to classify participants in the three sleep status groups
and to describe the sample. All other measures were used to
derive dependent variables.
Sleep measures
The ISI [37] is a seven-item questionnaire assessing the
nature, severity, and impact of sleep difficulties. Dimensions
are severity of sleep onset, sleep maintenance, and early
morning awakening problems; sleep satisfaction; interfer-
ence of sleep difficulties with daytime functioning; notice-
ability of sleep problems by others; and distress caused by
the sleep difficulties. A five-point Likert scale (b0Q=not atall, b4Q=extremely) is used to rate each of these items,
yielding a total score ranging from 0 to 28. Scores can be
classified into four severity categories: absence of insomnia
(0-7), subthreshold insomnia symptoms (8–14), moderate
insomnia (15–21), and severe insomnia (22–28). The ISI has
adequate psychometric properties and is sensitive to
measure treatment outcome [39]. The French–Canadian
version of the questionnaire has good internal consistency,
test–retest reliability and convergent validity (r=.65 when
comparing with sleep diary) [40].
The PSQI [36] is a 19-item questionnaire evaluating
sleep quality and disturbances over a 1-month time interval.
The first four items are open questions, whereas items 5 to
19 are rated on a four-point Likert scale. Individual items’
scores yield seven components: subjective sleep quality,
sleep latency, sleep duration, habitual sleep efficiency, sleep
disturbances, use of sleep-promoting medication, and day-
time dysfunction. A total score, ranging from 0 to 21, can be
obtained by adding the seven component scores. A score
higher than 5 suggests poor sleep quality. Psychometric
properties of the PSQI are adequate, especially regarding
the diagnostic sensitivity (89.6%) and specificity (86.5%)
for psychophysiological insomnia. The validated French–
Canadian version has adequate psychometric properties as
well [40].
Sleep-promoting products (i.e., prescribed and over-the-
counter medications) utilization was assessed with the
following questions: bDuring the past month, how many
nights per week have you taken prescribed medication to
help you sleep?Q and bDuring the past month, how many
nights per week have you taken over-the-counter medication
(e.g., Nytol, Sominex) to help you sleep?QPersonal and familial histories of insomnia were meas-
ured with the following questions: bIn the past, have you
ever experienced insomnia a few days per week for more
than 1 month? (yes/no),Q bIs a member of your immediate
family (parents, children, brothers, sisters) currently expe-
riencing sleep difficulties? (yes/no),Q and bHas a member of
your immediate family (parents, children, brothers, sisters)
ever experienced sleep difficulties? (yes/no).Q For those
answering in the affirmative, follow-up questions asked for
identifying the family member(s) and the type of sleep
problem (insomnia, excessive daytime sleepiness, sleep
apnea, restless legs or periodic limb movements, etc.). A
M. LeBlanc et al. / Journal of Psychosomatic Research 63 (2007) 157–166160
family history of insomnia was defined as a report of at least
1 parent or sibling with past or current insomnia.
Psychological measures
The Beck Depression Inventory II (BDI-II) [41] contains
21 items rating depressive symptoms experienced during the
past 2 weeks on a four-point Likert scale. A total score
(ranging from 0 to 63) is derived with a higher score
suggesting a higher depressive symptomatology. The cutoff
score for depressive symptoms of moderate severity is 20
[41]. The psychometric properties of the French version are
well documented and equivalent to those of the original
version [41].
The Trait part of the State-Trait Anxiety Inventory
(STAI-Trait) [42] was used to assess anxiety as a personality
trait. The STAI-Trait is comprised of 20 items rated on a
4-point Likert scale (b1Q=not at all, b4Q=a lot). Participants
have to score how they relate to the statements in general.
Total score range from 20 to 80, and 59 was used as the
cutoff score reflecting clinically significant anxiety. This
cutoff score represents two standard deviations (S.D.) above
our sample mean. Psychometric properties of the STAI are
excellent [40] as well as the validated French–Canadian
adaptation used in the present study [43].
Stress-related measures
The Perceived Stress Scale (PSS) [44] is a 14-item self-
report scale measuring the degree to which situations in one’s
life are appraised as stressful. Items represent feelings and
thoughts that have occurred in the past month in relation to
stressful situations or events. Individuals rate the frequency
of each item on a 5-point Likert scale (b0Q=never, b4Q=veryoften). The higher the total score, the more the person
appraises life as unpredictable and uncontrollable. The PSS
has adequate test–retest reliability (.85) and internal con-
sistency (.80) and is correlated with a range of self-report and
behavioral criteria [44]. A French–Canadian version of the
questionnaire was used in the present study.
The Coping Inventory for Stressful Situations (CISS)
[45] is a 48-item self-report measure of coping. It is divided
into three subscales, each containing 16 items: task-oriented
coping, emotion-oriented coping, and avoidance-oriented
coping. CISS items illustrate different ways of coping, and
respondents are asked to rate on a 5-point scale (b1Q=not atall, b5Q=very much) how each item is representative of their
own ways of coping with stress. The higher the score for a
scale, the more likely the respondent tends to rely on the
type of coping strategies measured by the scale. The CISS
has adequate properties with internal alpha reliabilities
ranging from .76 (men on the emotion subscale) to .91
(women on the task subscale) [45,46]. A French–Canadian
version of the questionnaire was used in the present study.
Arousal predisposition
The Arousal Predisposition Scale (APS) [24] is a 12-item
inventory that has been designed to measure arousability.
Respondents are asked to report the frequency to which they
experience the proposed emotion or behavior on a 5-point
Likert scale (b1Q=Never, b5Q=Always). The APS is a useful
measure of individual differences in predisposition towards
arousability and presents an adequate internal consistency
(0.84) [47]. A French–Canadian version of the measure
was used.
Personality
The NEO Five-Factor Inventory (NEO-FFI) [48] is a
60-item questionnaire measuring five personality domains:
neuroticism (N), extraversion (E), openness (O), agree-
ableness (A), and conscientiousness (C). Each factor is
evaluated by 12 items rated on a 5-point Likert scale
(strongly disagree to strongly agree). This five-factor model
is considered an excellent representation of personality [49].
The psychometric properties of the NEO-FFI in a Canadian
context have been considered adequate with internal
consistency coefficients of at least .70 for each of the five
subscales [50]. A French-Canadian version was used in the
present study [51].
Health-related quality of life
The SF-12 Health Survey version 2 [52] is a short form of
the SF-36, the most widely used health survey. The 12 items
are rated on a 5-point Likert scale, and eight subscale scores
can be derived from the answers (physical functioning, role
physical, bodily pain, general health, vitality, social func-
tioning, role emotional, and mental health). The psycho-
metric properties of the SF-12 version 2 are adequate with
reliability coefficients for the eight subscales ranging from
0.73 to 0.87 in general population [53]. A French–Canadian
version was used.
Data analysis
Between-group comparisons (good sleepers, insomnia
symptoms, and insomnia syndrome) were performed using
chi-squares and analyses of variance (ANOVAs). When
significant, Pearson chi-squares were followed by three
post hoc comparisons, comparing each group to the others
in 2�2 contingency tables [54–56]. If the post hoc chi-
square was higher than the Bonferroni critical value, m2(1,
1 � a/c)=m2(1, 1 � .05/3)=5.73 [54], this comparison
was considered significant. For significant ANOVAs,
multiple comparisons were conducted using the Ryan-
Einot-Gabriel-Welsh F (REGW F) tests to ensure statisti-
cally powerful comparisons while controlling alpha error
inflation [57]. Then, following Baron and Kenny’s [58]
suggestion, factorial ANOVA (groups�gender) was used
to assess the moderating effect of gender on the
relationship between sleep status and insomnia correlates
(dependent variables). Lastly, a multivariate ordinal (three
levels: good sleepers, insomnia symptoms, and insomnia
syndrome) logistic regression with cumulative logit link
Table 1
Demographic characteristics of the sample
Variables
Good sleepers (n=493) Insomnia symptoms (n=308) Insomnia syndrome (n=147)
M (S.D.) M (S.D.) M (S.D.) F SA (%)
Age
42.6a (13.9) 44.5a,b (14.3) 46.2b (13.5) 3.98* .80
% (n) % (n) % (n) m2
Gender
Women 58.0a (285) 59.1a (182) 70.1b (103) 7.094 .17
Men 42.0 (206) 40.9 (126) 29.9 (44)
Marital Status
Single/divorced/widowed 40.1 (196) 40.8 (125) 48.3 (71) 3.25 .26
Married/common-law relationship 59.9 (293) 59.2 (181) 51.7 (76)
Education
Grade School 4.7 (23) 4.5 (13) 5.9 (9)
High School 44.3 (219) 43.1 (125) 50.0 (76) 4.29 .02
Junior College 21.9 (108) 23.4 (68) 22.4 (34)
University 29.1 (144) 29.0 (84) 21.7 (33)
Occupation
Working/Student 77.9 (381) 72.3 (219) 66.2 (96) 8.964 .92
Nonworking/retired 22.1a (108) 27.7b (84) 33.8b (41)
Family Income
V$60000 68.5 (318) 73.5 (211) 81.0 (111) 8.644 .90
z$60001 31.5a (146) 26.5a,b (76) 19.0b (26)
SA, strength of association.
For ordinal variables, SA was computed as squared Spearman correlation. For continuous variables, SA was computed as Eta squared. SA represents the
percentage of variance explained by the sleep quality for each of the dependent variables.
Means with different subscripts are significantly different on the REGW multiple comparison test.
4 Pb.05.
M. LeBlanc et al. / Journal of Psychosomatic Research 63 (2007) 157–166 161
function was performed to identify the most important
variables in predicting sleep status group membership
[59,60]. All predictors were entered in one step into the
regression equation. Variance inflation index and colli-
nearity tests were performed to investigate multicollinear-
ity among predictors. Alpha level was set at a two-tailed
5% for all analyses. Most analyses were performed using
SPSS (version 10; SPSS, Chicago, IL, USA) except the
logistic regression and multicollinearity tests that were
completed under SAS System for Windows, Release 9.1
(Cary, NC).
Results
Participants
The overall sample (n=953) included 60% women, and
participants’ mean age was 43.7 years (S.D.=14.0; range
18–83). Most participants were Caucasian (98%), had
completed at least a high school degree (94.1%), were
married or living with a partner (58.3%) and were working
(66.2%). Based on the information gathered in the telephone
survey, individuals who did not return the questionnaire
(n=365) were significantly younger (mean age, 39.9 years;
S.D. =15.4) [F(1,1360)=17.63, Pb.0001] and included a
lower proportion of women (51%) than responders [m2(1,
n=1362)=7.5, Pb.01]. There were no significant differences
between nonresponders and responders regarding marital
status and education, but there was a significant difference
regarding sleep satisfaction, with more nonresponders being
dissatisfied with their sleep (28.8%) than responders
(23.4%) [m2(1, n=1362)=4.2, Pb.05].
Sleep status
Five participants could not be classified in one of the
three groups because of missing data. Of the 948 remaining
participants, 493 (51.7%) were classified as good sleepers,
308 (32.3%) as having insomnia symptoms and 147
(15.4%) as having an insomnia syndrome. Of the last
group, 20 individuals did not fulfill all the insomnia
diagnostic criteria but used prescribed sleep medication for
at least three nights per week. ISI scores were significantly
different between groups. Good sleepers obtained lower
scores (M=3.7; S.D.=3.2) than the two other groups, and the
insomnia symptoms group (M=8.4; S.D.=4.4) presented
lower scores than the insomnia syndrome group (M=15.4;
S.D.=4.1) [F(2,945)=573.3, Pb.001]. The same pattern was
observed regarding PSQI scores: good sleepers showed
lower scores (M=3.6; S.D.=1.8) than the insomnia symp-
toms group (M=6.1; S.D.=2.7), which presented lower
scores than the insomnia syndrome group (M=10.2;
S.D.=3.1) [F(2, 945)=447.9, Pb.001].
Factors associated with insomnia
Table 1 presents demographic characteristics of the three
sleep status groups. Groups did not significantly differ
Table 2
Sleep, psychological, and health variables (n=948)
Good sleepers (n=493) Insomnia symptoms (n=308) Insomnia syndrome (n=147)
m2 SA% (n) % (n) % (n)
Sleep variables
Personal history of insomnia (yes) 18.3a (90) 35.3b (108) 54.4c (80) 78.9844 8.07
Familial history of insomnia (yes) 32.7 (161) 36.7 (113) 38.1 (56) 2.19 0.14
Psychological variables
BDI-II (score z20) 4.2a (17) 11.5b (33) 26.8c (38) 57.1644 6.00
STAI-Trait (score z59) 1.4a (7) 2.6a (8) 12.3b (18) 40.6144 3.28
M (S.D.) M (S.D.) M (S.D.) F
BDI-II 5.7a (5.9) 8.8b (7.4) 13.9c (9.0) 80.0944 14.20
STAI-Trait 37.1a (8.6) 40.0b (9.0) 46.6c (9.4) 64.9344 12.30
APS 29.9a (6.8) 31.7b (6.3) 34.8c (6.9) 31.1344 6.10
PSS 21.5a (6.6) 23.3b (6.9) 27.5c (8.2) 42.7344 8.30
CISS
Task-oriented coping 55.9 (9.5) 55.2 (9.9) 54.4 (9.9) 1.63 0.30
Emotion-oriented coping 37.8a (10.9) 39.8b (10.8) 45.4c (11.5) 27.0944 5.40
Avoidance-oriented coping 45.0a (11.0) 43.1b (11.3) 44.8a,b (10.0) 3.194 0.70
NEO-FFI
Neuroticism 15.5a (8.0) 17.5b (7.8) 22.4c (8.5) 42.1744 8.30
Extraversion 29.4a (6.3) 28.1b (6.5) 26.3c (5.9) 14.3144 3.20
Openness 26.4 (5.9) 27.3 (6.6) 26.1 (6.6) 2.59 0.60
Agreeableness 34.6 (5.1) 34.1 (5.9) 33.5 (5.6) 2.26 0.50
Conscientiousness 36.9 (5.8) 36.2 (6.3) 36.3 (5.7) 1.26 0.40
Health-related quality of life
SF-12 Health Survey
General Health 75.2a (17.8) 71.2b (19.1) 61.5c (23.3) 29.0844 5.80
Bodily Pain 87.6a (19.7) 82.8b (22.7) 71.3c (29.5) 30.0744 6.00
Social functioning 83.1a (19.8) 76.5b (21.6) 61.6c (24.9) 58.5844 11.00
Physical functioning 85.5a (24.7) 81.3b (25.9) 67.5c (34.3) 24.9644 5.00
Vitality 71.6a (15.2) 67.1b (17.8) 53.2c (22.0) 63.8844 12.90
Role physical 82.8a (19.8) 76.6b (22.0) 64.3c (25.6) 42.9344 8.5
Role emotional 81.4a (18.3) 74.2b (20.6) 61.4c (23.2) 59.0044 11.0
Mental health 73.1a (14.8) 67.7b (16.3) 55.2c (19.1) 71.6844 13.20
For ordinal variables, SA was computed as squared Spearman correlation. For continuous variables, SA was computed as Eta squared. SA represents the
percentage of variance explained by the sleep status group membership for each of the dependent variables.
Means with different subscripts are significantly different on the REGW multiple comparison test.
4 Pb.05.
44 Pb.01.
M. LeBlanc et al. / Journal of Psychosomatic Research 63 (2007) 157–166162
regarding marital status and education. In contrast, there
were significant differences between groups regarding age
[F(2,938)=4.0, Pb.05], gender [m2(2, n=946)=7.09, Pb.05],
occupation m2(2, n=937)=8.96, Pb.05], and family
income [m2(2, n=888)=8.64, Pb.05]. Post hoc comparisons
revealed that the good sleepers group was significantly
younger compared to the insomnia syndrome group but not
compared to the insomnia symptoms group, which, in turn,
did not significantly differ from the insomnia syndrome
group. The proportion of women was higher in the insomnia
syndrome group relative to the insomnia symptoms and
the good sleepers groups. Regarding occupation, the
proportion of individuals working or studying was higher
in the good sleepers group compared to the insomnia
symptoms and syndrome groups. Lastly, the proportion of
individuals with higher incomes was higher in the good
sleepers group compared to the insomnia syndrome group
but not relative to the insomnia symptoms group.
Table 2 presents data for insomnia history (personal and
familial), psychological variables, and health-related quality
of life. There were significantly more individuals reporting
a previous episode of insomnia in the insomnia syndrome
group than in the two other groups and in the insomnia
symptoms group compared to good sleepers. There was no
significant between-group difference for family history of
insomnia, although good sleepers presented a lower
proportion than the other groups. For psychological
measures, both the BDI-II and the STAI-Trait mean scores
were significantly different among the three groups. When
BDI-II scores were computed without the item assessing
sleep disturbances, group means were still significantly
different (5.3 for good sleepers, 7.9 for insomnia symptoms
and 12.5 for insomnia syndrome) [F(2,938)=70.15, Pb.01].
The proportion of individuals presenting a score z20 was
significantly different between groups, as was the proportion
of individuals presenting a STAI-Trait score z59. The were
Table 3
Three-category (good sleepers, insomnia symptoms, and insomnia syn-
drome) ordinal logistic regression results (n=931)
Analysis of estimates
Predictors
Odds
ratio point
estimatea
95% Wald
confidence
limits
Wald
chi-square P
Previous episode
of insomnia
2.55 1.91 3.40 40.82 b.01
BDI-II 1.05 1.02 1.08 11.12 b.01
STAI-Trait 0.99 0.96 1.03 0.12 .73
PSS 1.00 0.97 1.03 0.05 .81
CISS
Emotion-oriented
coping
1.00 0.98 1.02 0.00 .95
APS 1.01 0.99 1.04 1.51 .30
NEO-FFI
Neuroticism 0.99 0.96 1.02 0.45 .50
Extraversion 1.00 0.97 1.02 0.19 .66
SF-12 health survey
General health 1.00 0.99 1.01 0.00 .97
Bodily pain 0.99 0.99 1.00 0.49 .48
Social functioning 1.00 0.99 1.01 0.42 .52
Physical functioning 1.00 0.99 1.00 0.34 .56
Vitality 0.99 0.98 1.00 5.37 .02
Role physical 0.99 0.98 1.00 2.87 .09
Role emotional 0.99 0.99 1.00 1.77 .18
Mental health 0.99 0.98 1.00 2.29 .13
a This odds ratio is estimated by exponentiating the corresponding
parameter estimate of h, B.
M. LeBlanc et al. / Journal of Psychosomatic Research 63 (2007) 157–166 163
also significant differences on the PSS, the CISS emotion-
oriented coping subscale, the APS, and the NEO-FFI
neuroticism and extraversion subscales, with the insomnia
syndrome group presenting higher scores than the two other
groups and the insomnia symptoms group presenting higher
scores than good sleepers. Scores on the CISS avoidance-
oriented coping subscale were significantly higher for the
good sleepers group compared to the insomnia symptoms
group but not compared to the insomnia syndrome group. For
health-related quality of life, all SF-12 subscales were
significantly different across groups. The insomnia syndrome
group showed scores suggesting a poorer quality of life
than the two other groups, and the insomnia symptoms group
showed scores suggesting a poorer quality of life than
good sleepers.
Factorial ANOVAs (group�gender) were conducted to
control for the effect of a higher proportion of women than
men in the sample. Results showed that gender did not have
a moderating effect on the relationship between sleep status
and any of the psychological and health-related quality of
life variables.
A multivariate ordinal (three levels) logistic regression
was performed to identify the most important variables in
predicting sleep status membership. Variables entered in the
equation included previous episode of insomnia (yes/no),
BDI-II, STAI-Trait, APS, PSS, the CISS emotion-oriented
coping subscale, the NEO-FFI neuroticism and extraversion
subscales, and the eight SF-12 subscales. A total of 931
observations (listwise, missing n=22 cases or 2.3%) were
submitted to the analysis (483 good sleepers, 302 individ-
uals with insomnia symptoms, and 146 individuals with an
insomnia syndrome). Since two predictors exhibited high
variance inflation values (STAI-Trait=5.8; NEO-FFI neu-
roticism subscale=3.6) but no problems were noted on other
multicollinearity tests, no predictors were removed from the
logistic regression. The final model exhibited a moderate fit
between observed and predicted group membership
(pseudo-R2=.25, 57.0% of correct classification). Three
variables [i.e., previous episode of insomnia, BDI-II [odds
ratio (OR)=1.05], and SF-12 vitality subscale (OR=0.99)]
were significantly associated with the presence of an
insomnia syndrome, whereas one other SF-12 subscale
(role physical, OR=0.99) was near statistical significance
(see Table 3). Thus, individuals who previously experienced
insomnia were 2.55 (OR=2.55) times more at risk of being
classified in a more severe category of insomnia than those
who never experienced insomnia in the past. Moreover,
each increase of one point on the BDI-II is associated with a
5% increase (OR=1.05), and each increase of one point of
the SF-12 vitality subscale is associated with a 1% decrease
(OR=0.99) of the risk of being in a more severe category
(i.e., insomnia symptoms or syndrome).
Discussion
The present study reveals that almost all factors tradi-
tionally associated with insomnia in studies conducted with
selected clinical samples also emerge as insomnia correlates
in a population-based sample. Results suggest that individ-
uals with insomnia endorse more psychological symptoma-
tology and more impairments of quality of life than good
sleepers, with degree of impairment increasing linearly with
insomnia severity.
Results of this study highlight the critical role of mental
health in insomnia. Indeed, several mental health-related
variables (e.g., BDI-II, and SF-12 mental health) differed
significantly across groups, with depressive symptomatol-
ogy among the most reliable predictors of sleep status
group membership. Moreover, a considerable number of
individuals in the insomnia symptoms and syndrome
groups (11.5% and 26.8%, respectively) obtained BDI-II
scores z20, indicating depressive symptoms of at least
moderate intensity [41], compared to only 4.2% of good
sleepers exceeding that threshold. Several epidemiological
studies have already shown that individuals with insomnia
complaints present higher levels of depression and anxiety
symptoms than those without insomnia [6,10–12,61]. In the
present study, the distinction between insomnia symptoms
and syndrome showed that even when sleep difficulties
are less severe, anxiety, neuroticism and depressive
symptomatology are more salient than in good sleepers.
However, given that all these measures are highly
correlated, it is unclear whether this is reflecting different
M. LeBlanc et al. / Journal of Psychosomatic Research 63 (2007) 157–166164
psychological dimensions of insomnia or a more generic
psychological distress profile. Furthermore, those results
are similar to some previous studies that suggested that
the presence of neurotic symptoms, emotional inhibition
and an inability to discharge anger characterizes individuals
with insomnia [16–18,20,22]. Our study was innovative
in its use of the NEO-FFI, which provided an over-
view of emotional, attitudinal, and motivational styles,
rather than simply an assessment of symptoms of mental
health disorder.
Individuals with insomnia (i.e., symptoms or syndrome)
reported higher arousal predisposition than good sleepers,
suggesting that they were more psychologically aroused, not
only at bedtime but as a general trait feature. Those with
insomnia symptoms and syndrome also reported higher
scores on the PSS and on the CISS emotion-coping subscale
than good sleepers. These findings are consistent with our
previous study [21], which also showed that individuals
with insomnia presented higher levels of bedtime arousal,
perceived their lives as more stressful and relied more on
emotion-focused coping strategies than good sleepers.
Collectively, these findings support the model suggesting
that the relationship between daytime stress and nighttime
sleep is mediated by bedtime arousal [21]. Nonetheless, it is
only through prospective longitudinal studies that the
hypothesis that increased arousal is a predisposing factor
for insomnia development may be confirmed.
Lastly, we found that a previous episode of insomnia was
among the best predictors of sleep status group membership,
a finding also reported by Klink et al. [14]. The rate of prior
history of insomnia among the insomnia syndrome (51%)
was similar to those observed in previous studies (44% [62];
56% [14]). Thus, these results would indicate that insomnia
is a recurrent problem for most people. Unlike previous
studies [31,32] however, there was no relation between
family history of insomnia and presence of insomnia
symptoms and syndrome.
This research has some limitations, including its cross-
sectional nature, which precludes any definite conclusions
about the direction of the relation between insomnia and its
correlates. Do psychological factors and health-related
quality of life play a role in the development of sleep
difficulties as predisposing factors, precipitating factors or
consequences? Personal and family history of insomnia,
arousal predisposition, and personality traits are generally
conceptualized as predisposing factors to insomnia,
whereas health-related quality of life is usually considered
as a consequence of insomnia. However, further longitudi-
nal studies are needed to corroborate those hypotheses. The
lack of differentiation between primary insomnia and
insomnia secondary to a mental, medical, or other sleep
disorder also warrants a cautious interpretation of the
results. Significant physical and mental health problems are
frequently associated with insomnia and may have been
confounding factors in the observed associations between
sleep status and the variables measured. Insomnia could be
the consequence or a symptom of another difficulty, such as
depression or a chronic disease, and the fact that we did not
document the presence of physical and mental health
disorders with standardized diagnostic procedures restricts
the interpretation of our results. For example, the finding
that bodily pain and physical conditions are important
variables in predicting group membership could be
explained by secondary insomnia, or on the other hand,
those two variables could simply reflect insomnia con-
sequences. Also, new independent variables like genetic,
cultural, environmental, lifestyle, and health-related varia-
bles (e.g., medical disorders, medication utilization) should
be further explored as potential insomnia correlates. Finally,
although the current sample was population-based, the
proportion of women and individuals dissatisfied with their
sleep was higher than in the general population, limiting
the generalization of the results.
Despite these limitations, this study sheds new light on
the topic of insomnia correlates. Firstly, with a population-
based sample that included both good sleepers and
individuals with different degree of insomnia severity, this
study may have captured a more accurate representation of
the association between sleep quality and psychological and
health-related quality of life correlates. The inclusion of
individuals with insomnia symptoms suggested that sleep
quality may be best illustrated by a continuum rather than
dichotomously and that insomnia correlates (e.g., depressive
symptoms and anxiety) may also follow the same pattern.
Psychological distress and quality-of-life impairment
increased with insomnia severity. Those results could also
guide the development of effective early intervention
programs to prevent chronic insomnia or the development
of other mental health disorders (e.g., major depression) as
soon as the first insomnia symptoms are noticed. Secondly,
this study focuses attention on the importance of rigorous
definition of insomnia with the utilization of a well-
operationalized algorithm, based on insomnia diagnostic
criteria from DSM-IV-TR [35] and ICD-10 [36], to deter-
mine the quality of participants’ sleep. Moreover, significant
between-group differences, both on the PSQI and the ISI,
support our sleep status classification algorithm, with scores
obtained on these two measures following a linear gradation
of sleep difficulties.
Longitudinal research is needed to assess the relative
contribution of those factors in the first onset and evolution
of insomnia over time. With repeated follow-up assess-
ments, we may also be able to identify risk factors for
insomnia and predictors or moderating variables of insom-
nia remission and relapse.
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