Wakefulness after sleep offset and the elevated risk of mortality in older adults with evening preferences: A...

This study investigated the relationship between wakefulness after sleep offset timing (WASF), evening chronotype preferences, and mortality risk in community-dwelling older adults.

We conducted a community-based longitudinal study with a sample of 4167 older adults aged ≥60. The sleep characteristics, WASF, subjective chronotype preferences, and other relevant variables of the participants at baseline were evaluated. We examined the association between WASF and mortality over a 5-year period using Cox proportional hazards models, with stratification by subjective chronotype preferences to explore potential effect modification.

Data from 3734 participants were analyzed (71.1 ± 6.9 years; 2114 [56.6 %] women). The 5-year mortality incidence was 6.3 %. Overall, participants had a median (IQR) of 5.0 (2-20) min WASF, and 767 (20.6 %) were evening types. WASF of ≤5 min = 10.6 (95 % CI, 8.9-12.8), WASF of >5 min = 14.6 (95 % CI, 12.1-17.6). The mortality incidence rates per 1000 person-years were: WASF of ≤5 min = 10.6 (95 % CI, 8.9-12.8) and WASF of >5 min = 14.6 (95 % CI, 12.1-17.6). Even after adjusting for covariates, the longer WASF participants had a higher hazard ratio of 1.40 (95 % CI, 1.04-1.88) compared to the shorter WASF participants. Regular, prolonged WASF was found to be significantly associated with an increased risk of mortality among evening-type individuals (2.69; 95 % CI: 1.19-6.08) in the stratified model based on subjective chronotype preferences. However, we found no statistically significant association among the other types.

Reducing morning time in bed, and addressing prolonged WASF are crucial factors in decreasing mortality risk among older adults, especially among those with evening preferences.