Sleep Characteristics and Prevalence of Perceived Insufficient Sleep Across Age Groups in the Japanese...

This study aimed to provide basic data according to age on objective sleep duration distribution and sleep characteristics via subjectivity, and to determine the prevalence of insufficient sleep and related sleep parameters in the general Japanese population. Data from the second survey of the Japan Multi-Institutional Cohort (J-MICC) Daiko Study were used for the analysis, with 2091 participants (1556 women; 58.6 ± 9.8 years old) included. Questionnaires included subjective sleep duration, perceived sufficiency, regularity, the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), Morningness-Eveningness Questionnaire (MEQ), and Epworth Sleepiness Scale (ESS). Sleep measurements were taken via actigraphy for one week. In total, 247 (11.8%) respondents reported insufficient sleep and 953 (45.6%) reported somewhat insufficient sleep. Working-age adults had shorter subjective and measured sleep durations than those aged ≥ 60 years. About 20% of those aged ≥ 50 years and more than 30% of those aged < 50 years reported ≥2 h of sleep deprivation. Perceived insufficient sleep was associated with irregular sleep but not sleep efficiency or sleep latency. Additionally, sleep duration perceived as insufficient varied among individuals. Individual differences in sleep duration and sleep efficiency were greater than those based on age. In conclusion, implementing measures to address sleep deprivation in Japan's working-age population are essential, and future epidemiological studies should consider individual differences.