Concurrence of Insomnia and Daytime Sleepiness Predicted 9-Year Mortality Risk in Community-Dwelling Older Adults: The Yilan Study, Taiwan

Abstract

Background: Co-occurring insomnia and daytime sleepiness has an undetermined clinical significance in older adults. We aimed to investigate the relationship between various combinations of insomnia and daytime sleepiness with mortality risk in community-dwelling older adults. The moderation effect of sex was also assessed.

Methods: We conducted this follow-up study including community-dwelling adults aged ≥65 in Yilan City, Taiwan. Daytime sleepiness was defined as scoring ≥11 on the Epworth Sleepiness Scale. Insomnia was defined as scores ≥5 on the Athens Insomnia Scale-5. Four phenotypes were defined based on the presence of insomnia or daytime sleepiness. The 9-year mortality risks for various phenotypic combinations were estimated using Cox regression analysis. Sex-specific risks were examined using an interaction term.

Results: In total, 2 702 older adults participated in the study, and 59.1% were women. The total 9-year mortality rate was 27.5%. After adjusting for all covariates, compared with those without insomnia or daytime sleepiness, the phenotype of co-occurring insomnia with daytime sleepiness predicted higher mortality risk (hazard ratio [HR]: 1.76, confidence interval [CI]: 1.20-2.58). In contrast, insomnia and daytime sleepiness alone did not correlate with higher mortality. The interaction between sex with co-occurring insomnia and daytime sleepiness was significant (p = .01). When stratifying by sex, the association between co-occurring insomnia and daytime sleepiness with higher mortality risk was male-specific (HR: 3.07, CI: 1.87-5.04).

Conclusions: Concurrence of insomnia and daytime sleepiness indicates a toxic phenotypic combination in older adults, particularly in men. Precise public health and preventive medicine can be implemented through geriatric sleep medicine.

Keywords: Daytime sleepiness; Insomnia; Mortality risk; Sex difference.