Insomnia in the elderly population: a study in hospital clinics of Tehran, Iran

In a study of more than 9000 community-dwelling adults over 65 years, 42% reported difficulty in initiating and maintaining sleep (Foley et al., 1995). A comprehensive review by Ohayon revealed that in non-institutionalized elderly people, difficulty in initiating sleep was reported by 15–45%, disrupted sleep by 20–65%, early morning awakenings by 15–54% and non-restorative sleep (NRS) by 10% (Ohayon, 2002). Fifty-two per cent of primary care adult patients with probable insomnia reported discussing this with a physician (Aikens and Rouse, 2005). The prevalence of insomnia in primary care patients was 69% (Shochat et al., 1999) and approximately 40% in community-dwelling adults (Roth and Ancoli-Israel, 1999). This study was conducted as the first attempt in Iran to clarify the clinical and characteristic conditions of elderly patients complaining about insomnia. This was a cross-sectional study, in which we assessed sleep problems in older adults in six hospital clinics in Tehran, Iran. Six hundred and ninety-six individuals (382 females and 283 males), age range 65–90 years, were selected randomly and were requested to complete a questionnaire comprising three parts: demographic questions, Insomnia Severity Index (ISI) and Pittsburg Sleep Quality Index (PSQI). The ISI, a standard questionnaire (Bastien et al., 2001), has an adequate internal consistency and is a valid self-report measure to evaluate perceived sleep difficulties based on DSM-IV insomnia criteria (Bastien et al., 2001). For the present study, it has been translated into Persian and has been checked for validity and reliability. The ISI comprises seven items assessing the severity of sleep onset and maintenance difficulties, satisfaction with current sleep pattern, interference with daily functioning, daytime impairment attributed to sleep problem and degree of distress or concern caused by sleep problem. Each item is rated on a 0–4 scale and the total score ranges from 0 to 28. Higher scores suggest more severe cases of insomnia (Bastien et al., 2001). A total score of 8 or above is considered to indicate probable insomnia (The Gallop Organization, 1991). Further categorization addresses subcategories of probable insomnia (Morin, 2008): ISI scores of 8–14 = mild, 15– 21 = moderate and 22–28 = severe insomnia. The PSQI is also a reliable and valid instrument assessing sleep quality and disturbances over a 1-month time interval (Buysse et al., 1989). The PSQI has seven subcategories: sleep quality, sleep latency, sleep duration, habitual sleep efficacy, sleep disturbances, medication use and daytime dysfunction. While our definition of probable insomnia is based on the ISI, we sought for a possible association between some PSQI questions and probable insomnia. The data were analysed by chi-squared test, t-test and multiple logistic regression. Our findings showed that 413 subjects (62.1%) were suffering to some extent from probable insomnia (28.7% from mild insomnia, 23.5% from moderate insomnia and 9.9% from severe insomnia). Probable insomnia was significantly higher among elderly women than men (odds ratio, OR 2.6, 95% confidence interval, CI 1.87–3.65). Difficulty in breathing and pain were also associated with higher risk of probable insomnia. Among other evaluated variables, level of education, general health satisfaction, general sleep satisfaction, use of drugs without prescription, percentage of habitual sleep efficiency (%HSE) and having problems maintaining enough enthusiasm to perform work were shown to be associated significantly with sleep problems. As to whether the participants had any problem maintaining enough enthusiasm to perform work, the findings indicated that the less the elderly had problem maintaining enough enthusiasm, the less they were at risk of probable insomnia (OR 0.21 for those having no problem versus those having many problems, 95% CI 0.09–0.52). Lower education was associated with higher risk of probable insomnia. The more satisfied the elderly with their general health or general sleep satisfaction, the less they suffered from probable insomnia; the better the general health satisfaction or general sleep satisfaction, the lesser the risk of probable insomnia. Taking medication without prescriptions also tripled the risk of probable insomnia (OR 3.21, 95% CI 1.32–7.83). The simultaneous effect of these variables was assessed through a multiple logistic regression. Our findings indicated that having problems maintaining enough enthusiasm to perform work, pain, general health satisfaction and general sleep satisfaction were the independent variables with the most significant impact on probable insomnia. Finally, we compared four of the major recent surveys in the field of elderly population insomnia with our work. Such a comparison may provide some important cross-cultural data in the field. To this end, we used the first four questions of the ISI; that is, difficulty with initiating sleep (DIS), disrupted sleep (DS), early morning awakening (EMA) and NRS. In our survey, DIS, DS, EMA and NRS were estimated to be 30.6%, 40.0%, 35.8% and 38.0% respectively (these percentages pertain to severe and very severe combined). In a survey conducted in Italy (Ohayon and Smirne, 2002), DIS was reported to be as high as 13.1%, which showed that sleep initiation was a far larger problem for the subjects of our survey (almost 2.7 times greater). Although their finding on DS was very similar to ours (34.1%) there is considerable J. Sleep Res. (2009) 18, 481–482 Letter to the Editor