Long and short sleep durations can affect cognitive function in older adults through the chain mediation effect of ADL and depression: evidence from CHARLS2018

Background: Both long and short sleep durations may lead to cognitive decline in the elderly individuals, though the underlying mechanisms remain unclear.

Aims: To explore the mediating mechanism of activities of daily living and depression on different sleep durations and cognitive function in older Chinese older adults.

Methods: This retrospective study used data from 5,899 older adults who completed the 2018 China Health and Retirement Longitudinal Surveys. We used the PROCESS macro in SPSS to determine the chain mediating effect of ADL and depression on the relationship between different sleep durations and cognitive functions.

Results: (1) There were significant correlations among sleep duration, ability to perform ADL, depression, and cognitive function. (2) For sleep durations ≤ 7 h/night or > 7 h/night, ADL and depression play a chain mediating role in the relationship between sleep duration and cognitive function.

Conclusions: Shorter or longer sleep durations were associated with cognitive decline by weakening ADL and worsening depression, which suggests that medical personnel should take action to correct abnormal sleep duration in older adults. Timely treatment of ADL impairment and depression may help prevent cognitive decline.