Sleep Duration and Disability-Free Life Expectancy Among Japanese Older Adults: The Ohsaki Cohort 2006 Study

Healthy life expectancy has been a useful indicator of population health that combines length and quality of life into a single measure,1 which is usually defined as the number of years living in optimal health without diseases and/or disability. Both shorter and longer sleep durations are related to adverse health outcomes; therefore, it is likely that an optimal sleep duration may be related to longer healthy life expectancy in older people. However, only 1 study has investigated the association between sleep duration and healthy life expectancy.