Background. Insomnia and disability pension are major health problems, but few population-based studies have examined the association between insomnia and risk of disability pension. Methods. We conducted a prospective nationwide cohort study based on Swedish population-based registers including all 5,028,922 individuals living in Sweden on December 31, 2004/2005, aged 17–64 years, and not on disability or old age pension. Those having at least one admission/specialist visit with a diagnosis of disorders of initiating and maintaining sleep (insomnias) (ICD-10: G47.0) during 2000/2001–2005 were compared to those with no such inpatient/outpatient care. All-cause and diagnosis-specific incident disability pension were followed from 2006 to 2010. Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were estimated by Cox regression. Results. In models adjusted for prior sickness absence, sociodemographic factors, and inpatient/specialized outpatient care, associations between insomnia and increased risks of all-cause disability pension (IRR 1.35, 95% CI 1.09–1.67) and disability pension due to mental diagnoses (IRR 1.86, 95% CI 1.38–2.50) were observed. After further adjustment for insomnia medications these associations disappeared. No associations between insomnia and risk of disability pension due to cancer, circulatory, or musculoskeletal diagnoses were observed. Conclusion. Insomnia seems to be positively associated with all-cause disability pension and disability pension due to mental diagnoses. 1. Introduction Insomnia is defined as complaint of or difficulty initiating or maintaining sleep or experiencing nonrestorative sleep that impairs daily social, occupational, or other functioning [1, 2]. Insomnia is a large and increasing health problem worldwide [3–5], associated with substantial costs for individuals, employers, and society [3]. The prevalence of insomnia in the adult population ranges from 4 to 50%, while fewer, that is, about 6–15%, are diagnosed with insomnia [1, 2, 4, 6]. The etiology of sleep disorders such as insomnia is multifactorial [7] and studies have shown that such disorders are associated with older age, female sex, low socioeconomic status (SES), and work-related stress [2, 3, 7, 8]. Moreover, insomnia has been suggested to adversely influence quality of life [1], work capacity [9], and endocrinology, immunology, and metabolism [10]. Thus, insomnia is associated with a wide range of health problems and diseases such as hypertension, inflammation, obesity, cardiovascular disease, cognitive and intellectual
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