Psychiatry and Clinical Neurosciences 2014
doi:10.1111/pcn.12252
Regular Article
Prevalence of insomnia and its clinical correlates in a general population in Turkey Gulcin Benbir, MD,1* Ahmet Ugur Demir, MD,2 Murat Aksu, MD,5 Sadik Ardic, Hikmet Firat, MD,3 Oya Itil, MD,6 Fuat Ozgen, MD,4 Hikmet Yılmaz, MD7 and Derya Karadeniz, MD, PhD1
MD,3
1
Sleep Disorders Unit, Department of Neurology, Istanbul University Cerrahpasa Faculty of Medicine, Istanbul, Department of Chest Diseases, Faculty of Medicine, Hacettepe University, 3Sleep Disorders Diagnosis and Treatment Center, Ministry of Health Diskapi Yildirim Beyazit Training and Research Hospital, 4Department of Psychiatry, Gulhane Military Academy of Medicine, Ankara, 5Department of Neurology, Faculty of Medicine, Erciyes University, Kayseri, 6 Department of Chest Diseases, Faculty of Medicine, Dokuz Eylül University, Izmir, and 7Department of Neurology, Faculty of Medicine, Celal Bayar University, Manisa, Turkey 2
Aim: The prevalence of insomnia is influenced by environmental factors. This study aimed to investigate the prevalence of insomnia and its sociodemographic and clinical correlates in a general population-based survey in Turkey. Methods: This population-based study included 4758 subjects among 5021 who participated in the Turkish Adult Population Epidemiology of Sleep Disorders study. Questionnaire items evaluating insomnia were adapted from the International Classification of Sleep Disorders II and the DSM-IV-TR. Subjects with restless legs syndrome were excluded. Results: Insomnia was found to be associated with older age (18–24 years, 9.8%; 25–44 years, 11.7%; 45–64 years, 13.8%; 65 years or older, 13.9%), lower income level ( 0.70). Informed consent was obtained from all participants, and ethical approval (HEK 10/34-
Study population analyzed for insomnia (n = 4758, F/M: 2407/2351)
25) was obtained from the Scientific Research Assessment Commission of Hacettepe University. Table 1 shows the definition of characteristics pertaining to the analysis. The Charlson Morbidity Index was used to assess the presence of systemic diseases diagnosed by a physician.16 Height and weight measurements were obtained when the subjects were in light clothes and without shoes, to the nearest 1 cm and 0.5 kg, respectively.
Statistical analysis Prevalence percentages of insomnia were provided by demographic and personal characteristics. No weighting procedures for stratification were applied,
© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology
4 G. Benbir et al.
Psychiatry and Clinical Neurosciences 2014
Table 1. Definition of the characteristics used in the analysis Characteristic
Related question
Definition
Smoking status
1. Have you ever regularly smoked cigarettes? (Regular refers to at least one cigarette for a year). Do you still smoke?
Income level†
What is the average monthly income per year for your household, including salary, lease, rent?
Time in front of TV
How long do you spend in front of TV during weekdays?
Education level
Which school did you graduate last?
Tea consumption
How frequently do you consume well-brewed tea (black tea) in the evening?
Coffee consumption
How frequently do you consume instant coffee in the evening?
Regular exercise‡
How frequently do you exercise? How long do you exercise in each session?
Working status
How do you earn your living? What is your occupation?
Schedule of work§
Which is the schedule of your work?
Never smoked: ‘No’ to both questions Ex-smoker: ‘Yes’ to first question and ‘No’ to second question Current smoker: ‘Yes’ to both questions 1 cup Exercising at least 5 times a week for a minimum of 30 min in each session Paid job Lease payments Retired Housewife Unemployed Owns a business Student Always during the day Always during the night 12-h shift 8-h shift Other
† Income levels were converted to USD based on the currency as of the time of the study. ‡Information was obtained from questions about exercising habits, frequency, type of exercise, duration of each session. Playing football was excluded. §This question was asked to subjects who were working during the time of the study. Night-time/shift schedule was defined by the responses of always during the night, or 12-h shift, or 8-h shift.
© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology
Psychiatry and Clinical Neurosciences 2014
as the sample design ensured proportional representation of strata. Comparisons between groups were tested by χ2 for categorical variables. Odds ratios and 95% confidence intervals (CI) were calculated as relative risk estimates. Logistic regression analysis was used in the assessment of association between insomnia and potential risk factors. Adjustments were made for age and sex. Model selection was performed by forward stepwise selection to assess the association between potential risk factors and insomnia. Interaction with age and sex were investigated in the same models constructed in different sex and age groups. A two-sided P-value less than 0.05 was considered as significant in all statistical comparisons.
RESULTS Of the 5021 participants, 2597 were female (51.7%). Age distribution of the study population was as follows: 742 participants (14.8%) were aged 18–24 years; 2389 participants (47.6%) were aged 25–44 years; 1469 participants (29.3%) were aged 45–64 years; and 418 participants (8.3%) were older than 64 years. Upon questioning, 263 patients (190 women) were excluded from the study because they were diagnosed as having RLS and/or the presence of recent initiation, change in dose or cessation of medication (Fig. 1). Among the remaining 4758 subjects, seven reported chronic (≥1 month) use of benzodiazepines, three of these subjects had insomnia; 31 reported chronic (≥1 month) use of other medications, such as antihistamines, mirtazapine or herbal remedies that have a narcoleptic effect, and 20 of these had insomnia. In the 4758 patients enrolled in this study, the overall prevalence was 51% for any symptom of insomnia, and 12.2% for insomnia (men, 8.6%; women, 15.7%). On the basis of ICSD-II criteria, subtypes of insomnia were as follows: 42.2% had difficulty in initiating sleep; 24.6% had difficulty in maintaining sleep; 24.6% had early morning awakenings; 5.8% had non-restorative sleep; and 2.8% had at least two combinations of these. Table 2 shows the crude and adjusted association between insomnia and other variables. Prevalence of insomnia was observed to increase with age, and then level off up to the age group of 45–64 years. In multiple logistic regression analysis adjusting for sex, age and each of the factors selected to the model, insomnia was significantly associated with: household income (odds ratio [OR], 0.5–0.6 for income levels more
Prevalence and correlates of insomnia 5
than 500 USD); time spent watching TV (OR, 0.6–0.7 for 1–6 h compared to
doi:10.1111/pcn.12252
Regular Article
Prevalence of insomnia and its clinical correlates in a general population in Turkey Gulcin Benbir, MD,1* Ahmet Ugur Demir, MD,2 Murat Aksu, MD,5 Sadik Ardic, Hikmet Firat, MD,3 Oya Itil, MD,6 Fuat Ozgen, MD,4 Hikmet Yılmaz, MD7 and Derya Karadeniz, MD, PhD1
MD,3
1
Sleep Disorders Unit, Department of Neurology, Istanbul University Cerrahpasa Faculty of Medicine, Istanbul, Department of Chest Diseases, Faculty of Medicine, Hacettepe University, 3Sleep Disorders Diagnosis and Treatment Center, Ministry of Health Diskapi Yildirim Beyazit Training and Research Hospital, 4Department of Psychiatry, Gulhane Military Academy of Medicine, Ankara, 5Department of Neurology, Faculty of Medicine, Erciyes University, Kayseri, 6 Department of Chest Diseases, Faculty of Medicine, Dokuz Eylül University, Izmir, and 7Department of Neurology, Faculty of Medicine, Celal Bayar University, Manisa, Turkey 2
Aim: The prevalence of insomnia is influenced by environmental factors. This study aimed to investigate the prevalence of insomnia and its sociodemographic and clinical correlates in a general population-based survey in Turkey. Methods: This population-based study included 4758 subjects among 5021 who participated in the Turkish Adult Population Epidemiology of Sleep Disorders study. Questionnaire items evaluating insomnia were adapted from the International Classification of Sleep Disorders II and the DSM-IV-TR. Subjects with restless legs syndrome were excluded. Results: Insomnia was found to be associated with older age (18–24 years, 9.8%; 25–44 years, 11.7%; 45–64 years, 13.8%; 65 years or older, 13.9%), lower income level ( 0.70). Informed consent was obtained from all participants, and ethical approval (HEK 10/34-
Study population analyzed for insomnia (n = 4758, F/M: 2407/2351)
25) was obtained from the Scientific Research Assessment Commission of Hacettepe University. Table 1 shows the definition of characteristics pertaining to the analysis. The Charlson Morbidity Index was used to assess the presence of systemic diseases diagnosed by a physician.16 Height and weight measurements were obtained when the subjects were in light clothes and without shoes, to the nearest 1 cm and 0.5 kg, respectively.
Statistical analysis Prevalence percentages of insomnia were provided by demographic and personal characteristics. No weighting procedures for stratification were applied,
© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology
4 G. Benbir et al.
Psychiatry and Clinical Neurosciences 2014
Table 1. Definition of the characteristics used in the analysis Characteristic
Related question
Definition
Smoking status
1. Have you ever regularly smoked cigarettes? (Regular refers to at least one cigarette for a year). Do you still smoke?
Income level†
What is the average monthly income per year for your household, including salary, lease, rent?
Time in front of TV
How long do you spend in front of TV during weekdays?
Education level
Which school did you graduate last?
Tea consumption
How frequently do you consume well-brewed tea (black tea) in the evening?
Coffee consumption
How frequently do you consume instant coffee in the evening?
Regular exercise‡
How frequently do you exercise? How long do you exercise in each session?
Working status
How do you earn your living? What is your occupation?
Schedule of work§
Which is the schedule of your work?
Never smoked: ‘No’ to both questions Ex-smoker: ‘Yes’ to first question and ‘No’ to second question Current smoker: ‘Yes’ to both questions 1 cup Exercising at least 5 times a week for a minimum of 30 min in each session Paid job Lease payments Retired Housewife Unemployed Owns a business Student Always during the day Always during the night 12-h shift 8-h shift Other
† Income levels were converted to USD based on the currency as of the time of the study. ‡Information was obtained from questions about exercising habits, frequency, type of exercise, duration of each session. Playing football was excluded. §This question was asked to subjects who were working during the time of the study. Night-time/shift schedule was defined by the responses of always during the night, or 12-h shift, or 8-h shift.
© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology
Psychiatry and Clinical Neurosciences 2014
as the sample design ensured proportional representation of strata. Comparisons between groups were tested by χ2 for categorical variables. Odds ratios and 95% confidence intervals (CI) were calculated as relative risk estimates. Logistic regression analysis was used in the assessment of association between insomnia and potential risk factors. Adjustments were made for age and sex. Model selection was performed by forward stepwise selection to assess the association between potential risk factors and insomnia. Interaction with age and sex were investigated in the same models constructed in different sex and age groups. A two-sided P-value less than 0.05 was considered as significant in all statistical comparisons.
RESULTS Of the 5021 participants, 2597 were female (51.7%). Age distribution of the study population was as follows: 742 participants (14.8%) were aged 18–24 years; 2389 participants (47.6%) were aged 25–44 years; 1469 participants (29.3%) were aged 45–64 years; and 418 participants (8.3%) were older than 64 years. Upon questioning, 263 patients (190 women) were excluded from the study because they were diagnosed as having RLS and/or the presence of recent initiation, change in dose or cessation of medication (Fig. 1). Among the remaining 4758 subjects, seven reported chronic (≥1 month) use of benzodiazepines, three of these subjects had insomnia; 31 reported chronic (≥1 month) use of other medications, such as antihistamines, mirtazapine or herbal remedies that have a narcoleptic effect, and 20 of these had insomnia. In the 4758 patients enrolled in this study, the overall prevalence was 51% for any symptom of insomnia, and 12.2% for insomnia (men, 8.6%; women, 15.7%). On the basis of ICSD-II criteria, subtypes of insomnia were as follows: 42.2% had difficulty in initiating sleep; 24.6% had difficulty in maintaining sleep; 24.6% had early morning awakenings; 5.8% had non-restorative sleep; and 2.8% had at least two combinations of these. Table 2 shows the crude and adjusted association between insomnia and other variables. Prevalence of insomnia was observed to increase with age, and then level off up to the age group of 45–64 years. In multiple logistic regression analysis adjusting for sex, age and each of the factors selected to the model, insomnia was significantly associated with: household income (odds ratio [OR], 0.5–0.6 for income levels more
Prevalence and correlates of insomnia 5
than 500 USD); time spent watching TV (OR, 0.6–0.7 for 1–6 h compared to
