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RESEARC H ARTIC LE Open Access
Insomnia and its correlates in a representative
sample of the Greek population
Thomas Paparrigopoulos
1*
, Chara Tzavara
2
, Christos Theleritis
1
, Constantin Psarros
1
, Constantin Soldatos
1
,
Yiannis Tountas
2
Abstract
Background: Insomnia is a major public health concern affecting about 10% of the general population in its
chronic form. Furthermore, epidemiological surveys demonstrate that poor sleep and sleep dissatisfaction are even
more frequent problems (10-48%) in the community. This is the first report on the prevalence of insomnia in
Greece, a southeastern European country which differs in several socio-cultural and climatic aspects from the rest
of European Community members. Data obtained from a national household survey (n = 1005) were used to
assess the relationship between insomnia symptoms and a variety of sociodemographic variables, life habits, and
health-related factors.
Methods: A self-administered questionnaire with questions pertaining to general health and related issues was
given to the participants. The Short Form-36 (Mental Health subscale), the Athens Insomnia Scale (AIS) as a
measure of insomnia-related symptoms, and the International Physical Activity Questionnaire (IPAQ) were also used
for the assessment.
Results: The prevalence of insomnia in the total sample was 25.3% (n = 254); insomnia was more frequent in
women than men (30.7% vs. 19.5%) and increased with age. Multiple regression analysis revealed a significant
association of insomnia with low socio-economical status and educational level, physical inactivity, existence of a
chronic physical or mental disease and increased number of hospitalizations in the previous year.
Conclusions: The present study confirms most findings reported from other developed countries around the
world regarding the high prevalence of insomnia problems in the general population and their association with
several sociodemographic and health-related predisposing factors. These results further indicate the need for more
active interventions on the part of physicians who should suspect and specifically ask about such symptoms.
Background
Insomnia is a major public health concern affecting about
10% of the general population in its chronic form. More-
over, epidemiological surveys demonstrate that poor
sleep and sleep dissatisfaction are even more frequent
problems in the community, ranging from 10-48%,
depending on the study [1-9]. Several correlates of
insomnia have been identified, such as sociodemographic
determinants, life habits, mental disorders and physical
illnesses [1]. It is generally acknowledged that women are
more likely than men to report insomnia symptoms, day-
time consequences of disturbed sleep and sleep
dissatisfaction, and consequently to receive a diagnosis of
insomnia [3-5,10-18]. Thus, women/men ratio for insom-
nia symptoms is approximately 1.4; this ratio increases
with age, reaching 1.7 after 45 years of age [1]. Also, the
vast majority of epidemiological studies report an
increased prevalence of insomnia symptoms and sleep
dissatisfaction with age, approaching 50% in the elderly
population [4,5,13-15,17,19,20], when it reaches a pla-
teau, women suffering more often than men from such
symptoms [1-5,21,22]. In regard to other sociodemo-
graphic determinants most studies report a higher preva-
lence of insomnia in separated, divorced, or widowed
individuals [4,5,16,17,23], women in particular [4,5], in
less privileged individuals of lower income [4,19], of
lower education [19,20,24] or unemployed [4,5,14,15,23];
* Correspondence: tpaparrig@med.uoa.gr
1
University of Athens Medical School, 1st Department of Psychiatry, Eginition
Hospital, Athens, Greece
Full list of author information is available at the end of the article
Paparrigopoulos et al.BMC Public Health 2010, 10:531
http://www.biomedcentral.com/1471-2458/10/531
© 2010 Paparrigopoulos et al; licensee BioMed Central Ltd. This is an Open Access article distri buted under the terms of the Creative
Commons Attri bution License (http://creativecommons.org /licenses/by/2.0), which permits unrestricted use, distribution, and
reproductio n in any medium, provided the original work is properly cited.
the highest risk of insomnia symptomatology has been
found in retired people, followed by housekeepers [5].
Regarding the various factors connected with insomnia
these have been divided into primary, secondary (mental
disorders, medical conditions, sleep disorders) and self-
induced factors (lifestyle, use, abuse or withdrawal of
psychoactive substance) [1]. For what concerns mental
health disorders in particular, insomnia symptoms may
be present in the large majority (over 80%) of indivi-
duals suffering from major depression and in more than
one third of cases with any mental disorder [1,25-30].
Furthermore, persistent insomnia symptoms may
increase the likelihood of developing major depressive
disorder [1,31] and may be a risk factor of physical
health problems as well [1,32].
This is the first report on the prevalence of insomnia
in Greece, a southeastern European country which dif-
fers in several socio-cultural and climatic aspects from
the rest of European Community members. Thus,
Greece has a warmer climate than the rest of Europe
and daylight hours are relatively extended compared to
other latitudes, which gives more opportunities for
social evening activities and leads to delayed bedtime
hours. Furthermore, in the Greek culture daytime nap-
ping remains a socially acceptable behavior, even in
large cities; although a continuous working schedule has
been operating in most cases during the last two dec-
ades, napping behavior still appears to be relatively pre-
valent in Greece. Finally, because strong emotional and
financial bonds still exist within both the core and
extended Greek family, housing conditions of the family
may differ from those in the other European countries.
The present study also investigates the relationship
between insomnia and a variety of sociodemographic
parameters, life habit factors and health factors in a
representative sample of the Greek population.
Methods
Sample
Data were obtained from the national household survey
Hellas Health I, conducted during 2006 by the Center of
Health Services Research of the Department of Hygiene
and Epidemiology, Medical School, University of Athens.
Candidate respondents were selected by means of a
three-stage, proportional-to-size sampling design. First, a
random sample of building blocks was selected propor-
tionally to size. Second, in each selected area of blocks,
thehouseholdstobeinterviewedwererandomly
selected by means of systematic sampling. Third, in
each household, a sample of individuals aged 18 years
or above was selected by means of simple random sam-
pling.Thesurveycoveredurbanareas(2000ormore
inhabitants) and rural areas all over Greece. Patients in
hospitals, sheltered homes, and homeless people were
not investigated.
Thesurveypopulationconsisted of 1005 individuals
and effective response rate reached 44.5%, which is a
fairly good rate for Greek standards. All participants
were interviewed face to face by trained interviewers.
The duration of the interview was 35-40 minutes. The
sample was representative of the Greek population in
terms of age and residence. Approval for the study was
obtained from the institutional review board of the
Athens University Medical School, and the protocol
conformed to the ethical guidelines of the 1975 Declara-
tion of Helsinki.
Assessments
A self-administered questionnaire including 146 ques-
tions or sub-questions and 13 open-ended questions
pertaining to general health and related issues was given
to the participants; the questionnaire had been pre-
tested in terms of the comprehension and the order of
the questions included. The socio-demographic ques-
tions were close-ended and included age, sex, marital
status, residency (urban vs. rural), educational level and
social class. Social class was based on the ESOMAR
1997 index categories (i.e., calculated on the basis of the
family’s main income earner’s job category and the level
of education and summed up into three social cate-
gories: A/B-C1 = upper/upper middle, C2 = lower mid-
dle and D/E = lower).
Self reported measures of weight (kg) and height (m)
were obtained by the questionnaire. Body mass index
(BMI) was calculated as weight/(height)
2
. Respondents
were also asked to report any chronic diseases from a
checklist of the leading causes of morbidity (i.e., dia-
betes, hypertension, hypercholesterolemia or other
chronic diseases); the number of chronic diseases of the
respondents was evaluated. Current smokers were
defined as those who smoked at least one cigarette per
day. Alcohol use was defined as at least one drink per
day. Physical activity was evaluated using the Interna-
tional Physical Activity Questionnaire (IPAQ) [33]. The
IPAQ was graded in qualitative terms as sedentary
(score on IPAQ less than 30), light (score on IPAQ
from 30 to 41.5), moderate (score on IPAQ from 42 to
59.5) and vigorous (score on IPAQ more than 60). Sub-
jects with score on IPAQ less than 30 were character-
ized as physically inactive.
Insomnia symptoms were assessed through the Athens
Insomnia Scale (AIS), which is an 8-item standardized
self-assessment psychometric instrument designed for
quantifying sleep difficulty based on the ICD-10 criteria.
It consists of eight items: the first five pertain to sleep
induction, awakenings during the night, final awakening,
Paparrigopoulos et al.BMC Public Health 2010, 10:531
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total sleep duration, and sleep quality; while the last
three refer to well-being, functioning capacity, and slee-
piness during the day [34]. A cut-off score of ≥6onthe
AIS was used to establish the diagnosis of insomnia
[35]. Mental health was assessed using the ‘mental
health summary score’from the Short Form-36 self-
administered questionnaire [36] (SF-36, Greek standard
version 1.0).
Variables
Insomnia was evaluated in association with the following
variables:
1. Sociodemographic factors: age, sex, marital status,
socioeconomical status and educational level.
2. Life habit factors: use of alcohol, tobacco and physi-
cal activity level.
3. Health factors: chronic disease, mental health, body
mass index and the number of hospitalizations in the
previous year.
Statistical analysis
Quantitative variables are presented with absolute and
relative frequencies. For comparisons between propor-
tions chi-square test was used. P_value for trend in the
prevalence of insomnia by age was also calculated. Uni-
variate logistic regression analyses were used to test the
effect of the factors under investigation on having
insomnia and data were modeled using logistic regres-
sion analysis. Odds ratios (OR) with 95% confidence
intervals (95% CI) were computed from the results of
the logistic regression analyses. All p values reported are
two-tailed; statistical significance was set at 0.05. Ana-
lyses were conducted using the SPSS statistical software
(version 13.0).
Results
Data from 1005 participants were analyzed. Sample
characteristics are presented in Table 1. The prevalence
of insomnia for the total sample was 25.3% (95% Confi-
dence Interval: 22.6% - 28.0%). Insomnia was more fre-
quent in women than men (30.7% vs. 19.5%, p < 0.001)
and increased by age (p for trend <0.001 - Figure 1).
Regarding the specific sleep complaints as reflected in
the AIS, these were mainly related to delayed sleep
onset and increased number of awakenings during the
night, both for men and women. Of the total sample,
29.2% had at least one of the items of AIS-8 rated as
‘markedly’or ‘severely impaired’; 11.5% reported that
their final awakening was at least ‘markedly earlier’than
desired, while 9.9% estimated that their total sleep time
Table 1 Sample characteristics
N (%)
Sex
Men 483 (48.1)
Women 522 (51.9)
Age (years)
18-24 115 (11.4)
25-34 185 (18.4)
35-44 180 (17.9)
45-54 151 (15.0)
55-64 150 (14.9)
> 65 224 (22.3)
Family status
Married 646 (64.3)
Single 244 (24.3)
Divorced/Widowed 115 (11.4)
Socioeconomic status*
Upper/upper middle (A/B-C1) 168 (16.7)
Lower middle (C2) 462 (46.0)
Lower (D/E) 375 (37.3)
Level of education
Low 334 (33.2)
Middle 422 (42.0)
High 249 (24.8)
Alcohol use
No 453 (45.1)
Yes 552 (54.9)
Smoking
No 572 (56.9)
Yes 433 (43.1)
Physical activity
No 478 (50.5)
Yes 469 (49.5)
Weight status
Normal (BMI < 25) 416 (42.4)
Overweight (25<BMI < 30) 404 (41.2)
Obese (BMI > 30) 161 (16.4)
Chronic disease
No 645 (64.2)
Yes 360 (35.8)
Hospitalizations in the past 12 months
None 880 (88.4)
One or more 115 (11.6)
Mental health problems
Present 50 (5.0)
Absent 955 (95.0)
SF-36 Mental health Component Score
Individuals with mental problems 37.6 (SD = 11.0)
Individuals without mental problems 48.1 (SD = 8.9)
*based on the ESOMAR 1997 index categories
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was at least ‘markedly unsatisfactory’; 10.2% of the total
sample (7.9% of men and 12.5% of women) complained
for their sleep quality. Complaints regarding well-being,
functioning and sleepiness during the day were made by
8.6%, 8.6% and 5.7% of the respondents (Table 2).
In univariate analysis odds for insomnia was lower for
single subjects and higher for divorced/widowed subjects
compared to married individuals but this association
was not significant in the multivariate analysis (Table 3).
Participants of low socioeconomical status suffered
more often from insomnia than those of high socioeco-
nomical status; this association remained significant
after adjusting for other variables (OR = 1.67, 95% CI:
1.03-2.69). The difference in the odds for insomnia was
not significant between individuals of low and indivi-
duals of middle socioeconomical status. The educational
level was a significant predictor for insomnia both in
univariate and multivariate analysis. Thus, individuals of
middle or high educational level had a lower likelihood
for having insomnia compared to those of low educa-
tional level. Alcohol and smoking were significant pre-
dictors in the bivariate analysis but did not make an
independent contribution to insomnia in the multivari-
ate analysis. On the other hand, physical activity was a
significant predictor for insomnia. Physically inactive
subjects had 1.42 greater odds for having insomnia in
the multivariate model. Obese subjects had a higher pre-
valence of insomnia than subjects of normal weight but
this association was not significant after adjusting for
other variables. Finally, chronic disease, the number of
hospitalizations in the previous year and mental health
significantly predicted insomnia in the multiple logistic
regression analysis with odds ratios 1.58 (95% CI:
1.06-2.34), 1.90 (95% CI: 1.18-3.05) and 0.96 (95% CI:
0.95-0.97) respectively.
Discussion
This is the first epidemiological study to evaluate the
prevalence of insomnia problems and its correlates in
the general population of Greece. Insomnia, as mea-
sured by the Athens Insomnia Scale (AIS), was reported
by 25.3% of the sample; prevalence of insomnia was sig-
nificantly higher in women than in men (30.7% vs.
19.5%) and considerably increased with age. These find-
ings are in accordance with the existing literature,
although estimates of the prevalence of insomnia may
widely vary depending on the applied definition of
insomnia and the methodology used [1]. In a large-scale
single-day survey in ten countries across the globe
where the Athens Insomnia Scale was used as a self-
assessment instrument, 31.6% of the subjects reported
to have ‘insomnia’while another 17.5% could be consid-
ered as having ‘sub-threshold insomnia’; however, in this
study important global variations in the prevalence of
insomnia were observed [37].
Marital and socioeconomic status is considered to be
of importance among the sociodemographic determi-
nants of insomnia. This was also replicated in the pre-
sent study. Thus, participants of lower socioeconomic
and educational level were more likely to suffer from
insomnia even after correction for possible confounding
factors such as sex and age. Furthermore, although in
univariate analysis the odds for insomnia was lower for
single subjects but higher for divorced or widowed sub-
jects compared to married individuals, this association
was not significant in multivariate analysis. Conse-
quently, marital status did not contribute in a significant
waytotheoccurrenceofinsomniacontrarytowhatis
generally reported in the literature, although this corre-
lation may be more prominent in the female population
[4,5,16,17,23].
Concerning life habits, which may affect sleep quality
and lead to non restorative sleep complaints [38], alcohol
and smoking were significant predictors for insomnia in
bivariate analysis but did not make an independent contri-
bution in the multivariate analysis. Clearly, more detailed
information on such habits is necessary in order to investi-
gate their potential influence on sleep, which was not pro-
vided by the study. On the other hand, physical activity
was a significant predictor for insomnia, i.e., physically
Figure 1 The prevalence of insomnia presented by sex and
age groups.
Table 2 Prevalence of sleep complaints (based on AIS) in
the total sample and by gender. Number of responders
(%) who estimate to have a ‘marked’or ‘severe problem’
in the eight AIS items
Total sample Men Women
AIS-8 individual items N (%) N (%) N (%)
Sleep induction 174 (17.3) 50 (10.4) 124 (23.8)
Awakenings during the night 147 (14.6) 50 (10.4) 97 (18.6)
Final awakening 116 (11.5) 46 (9.5) 70 (13.4)
Total sleep duration 99 (9.9) 34 (7.0) 65 (12.5)
Sleep quality 103 (10.2) 38 (7.9) 65 (12.5)
Well-being during the day 86 (8.6) 35 (7.2) 51 (9.8)
Functioning during the day 86 (8.6) 28 (5.8) 58 (11.1)
Sleepiness during the day 57 (5.7) 19 (3.9) 38 (7.3)
Paparrigopoulos et al.BMC Public Health 2010, 10:531
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inactive subjects were more at risk for having insomnia
compared to active individuals. Epidemiological surveys
have demonstrated sleep promoting benefits of moderate,
regular physical activity although experimental evidence
from sleep studies is not so compelling [39]; however, in a
recent study based on the same study population it has
been shown that physical activity may promote sleep in
cardiac patients suffering from insomnia [40].
Obesity was another predictor for insomnia but the
association was not significant after adjusting for other
variables. This is in line with the findings of another
large epidemiological study where it has been reported
Table 3 Prevalence of insomnia and associations derived by logistic regression analysis
Variable Insomnia, N (%) OR (95% CI)
Crude
OR (95% CI)
Adjusted
Sex
Men 94(19.5) 1.00 1.00
Women 160(30.7) 1.83* (1.37-2.45) 1.48‡(1.03-2.10)
Age (years)
18-24 9(7.8) 1.00 1.00
25-34 18(9.7) 1.26(0.55-2.93) 1.16(0.48-2.81)
35-44 33(18.3) 2.64‡(1.21-5.75) 2.09(0.90-4.83)
45-54 37(24.5) 3.82*(1.76-8.29) 2.68‡(1.17-6.14)
55-64 55(36.7) 6.82*(3.19-14.54) 3.63†(1.59-8.28)
> 65 102(45.5) 9.84*(4.74-20.42) 4.06†(1.79-9.17)
Family status
Married 179(27.7) 1.00 1.00
Single 23(9.4) 0.27* (0.17-0.43) 0.65(0.36-1.17)
Divorced/Widowed 52(45.2) 2.15* (1.44-3.23) 1.04(0.62-1.74)
Socioeconomic status
A/B-C1 30(17.9) 1.00
C2 116(25.1) 1.54(0.99-2.41) 1.40(0.88-2.24)
D/E 108(28.8) 1.86†(1.18-2.93) 1.67‡(1.03-2.69)
Level of education
Low 140(41.9) 1.00 1.00
Middle 73(17.3) 0.29* (0.21-0.40) 0.59‡(0.38-0.91)
High 41(16.5) 0.27* (0.18-0.41) 0.58‡(0.36-0.94)
Alcohol use
No 154(34.0) 1.00 1.00
Yes 100(18.1) 0.43* (0.32-0.58) 0.56 (0.41-1.19)
Smoking
No 165(28.8) 1.00 1.00
Yes 89(20.6) 0.64†(0.48-0.86) 0.96(0.65-1.41)
Physical activity
No 84(17.9) 1.00 1.00
Yes 153(32.0) 2.16* (1.59-2.92) 1.42‡(1.01-2.03)
Weight status
Normal (BMI < 25) 86(20.7) 1.00 1.00
Overweight (25≤BMI < 30) 100(24.8) 1.26(0.92-1.75) 0.78(0.52-1.16)
Obese (BMI≥30) 60(37.3) 2.28* (1.53-3.39) 1.06(0.66-1.72)
Chronic disease
No 100(15.5) 1.00 1.00
Yes 154(42.8) 4.07* (3.02-5.49) 1.58‡(1.06-2.34)
Hospitalizations in the past 12 months
None 201(22.8) 1.00 1.00
One or more 50(43.5) 2.60* (1.74-3.88) 1.90‡(1.18-3.05)
Mental health summary score (SF-36) 0.95*(0.94-0.96) 0.96*(0.95-0.97)
OR = Odds Ratio, CI = 95% Confidence Interval, ‡p<0.05,†p < 0.01, * p < 0.001
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that body mass index (BMI) was not significantly related
to non restorative sleep complaints [38]. This was some-
what unexpected because overweight people frequently
suffer from a variety of physical illnesses as well as sleep
apnea syndromes, which may have a considerable
impact on sleep; a more meticulous investigation of this
factor is therefore warranted in future epidemiological
studies. Regarding the other health factors investigated,
i.e., the presence of a chronic disease and mental health
problems, these significantly predicted insomnia in the
multiple regression analysis; this finding is in accordance
with the existing literature [1,29,30,41].
Conclusions
There are some inherent limitations to this epidemiolo-
gical study. First, prevalence of insomnia was not based
on objective measures, i.e., polysomnography or actigra-
phy data. Second, because the study was part of a gen-
eral health epidemiological survey, no detailed data
related to specific sleep disorders or sleep aids and med-
ications use were collected; finally, circadian sleep-wake
parameters, such as shift work, were not assessed.
Despite the above limitations, the present study con-
firmsmostfindingsreportedfromotherdeveloped
countries around the world, that is, the high prevalence
of insomnia problems in the general population (25.3%)
and their association with female sex, older age, a low
socio-economic-educational level, physical inactivity,
and the existence of a chronic physical or mental disease
in the previous year. These findings further indicate that
insomnia symptoms is a major public health issue, as
well as the need for more active interventions especially
on the part of mental health professionals who should
suspect and specifically ask about such symptoms, since
only a modest percentage (27-45%) of insomnia com-
plainers will discuss such problems with their physicians
[1-9].
Author details
1
University of Athens Medical School, 1st Department of Psychiatry, Eginition
Hospital, Athens, Greece.
2
University of Athens Medical School, Center for
Health Services Research, Athens, Greece.
Authors’contributions
ThP, ChTz, ChTh, and CP participated in the preparation of the paper. CS
and YT had overall supervision of the study. All authors read and approved
the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 25 April 2010 Accepted: 3 September 2010
Published: 3 September 2010
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Pre-publication history
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Cite this article as: Paparrigopoulos et al.: Insomnia and its correlates in
a representative sample of the Greek population. BMC Public Health 2010
10:531.
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