[Factors affecting insomnia among community-dwelling older adults]

Objectives　Insomnia is prevalent among older adults, individuals with depression, and women. It has been linked to hypertension and diabetes mellitus onset and increased risk of dementia, making it a major public health concern. It also affects quality of life and has broader social consequences, such as traffic accidents. The aim of this study was to identify the factors influencing insomnia among community-dwelling older adults using longitudinal data and provide insights to facilitate better sleep and inform future preventive measures.Methods　A self-administered questionnaire was mailed to 3,417 individuals selected from older adults living in 11 areas within Ward A of K City, Kanagawa Prefecture, where the proportion of people aged 65 years and older is relatively high. A similar survey was conducted among 1,755 individuals who agreed to participate in a follow-up survey two years later. The Athens Insomnia Scale (AIS) was used to measure the severity of sleep disorders. Multiple regression analysis (forced entry method) was performed using the AIS score as the dependent variable in the follow-up survey. The independent variables included sex, social network, instrumental independence, back pain, knee or joint pain, self-rated health, role at home, financial situation, and household status.Results　From participants with follow-up data, 917 were included in the analysis after excluding those who had died, were hospitalized, or had an AIS score of 6 or higher at baseline. The characteristics of the participants were as follows: mean age, 75.0 (SD＝5.7) years; 459 males (50.1%); mean social network score, 17.1 (SD＝5.9); median instrumental independence, 5; lower back/back pain, 257 individuals (28.0%); knee/joint pain, 200 (21.8%); self-rated poor health, 72 (7.9%); no role at home, 83 (9.1%); financial hardship, 55 (6.0%); living alone, 141 (15.4%). Multiple regression analysis (forced entry method) was conducted to examine the factors influencing the AIS scores at follow-up. The results showed significant associations of the AIS score with having a small social network and being female. The adjusted coefficient of determination (R²) was 0.312.Conclusion　Increasing social interactions and developing strategies that incorporate sex differences may help reduce insomnia in community-dwelling older adults.