Insomnia subtypes and their relationship to excessive daytime sleepiness in Brazilian community-dwelling older adults.

STUDY OBJECTIVES: To investigate the association between different types of insomnia as exposures and excessive daytime sleepiness (EDS) as a binary outcome in older Brazilian residents. DESIGN: The baseline examination of the Bambui Health and Ageing Study (BHAS), which is an ongoing population-based prospective cohort study of older adults. SETTING: Bambui (15,000 inhabitants), a city in the State of Minas Gerais, Southeast Brazil PARTICIPANTS: All residents aged ≥ 60 years were eligible to take part in the BHAS baseline. Of 1742 residents identified who were ≥ 60 years, 1606 (92.2%) were interviewed and received comprehensive examinations of health status. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: EDS was defined as the presence of sleepiness ≥ 3 times per week in the last month, causing any interference in usual activities. All insomnia subtypes were significantly associated with EDS in unadjusted analyses, and these associations were only modestly altered after adjusting incrementally for the other covariates. In a final model, the 3 insomnia subtypes were entered into a fully adjusted model simultaneously to investigate mutual independence, giving prevalence ratios of 1.63 (95% CI 1.14-2.31) for initial insomnia, 2.13 (95% CI 1.48-3.07) for middle insomnia, and 1.36 (95% CI 0.94-1.96) for terminal insomnia. The population attributable fractions for initial, middle, and terminal insomnia on prevalence of EDS were 17.6%, 32.9%, and 9.7%, respectively. CONCLUSIONS: Middle insomnia emerged as the insomnia subtype most strongly associated with EDS. Further research is required to clarify causal pathways underlying this cross-sectional association.