Relationship between objective sleep efficiency and psychological distress in middle-aged and older Japanese: Results by work in the Shika study

Sleep quality and work, as factors related to psychological distress, have not yet been elucidated. Additionally, few studies have examined the association between sleep efficiency and psychological distress, which may affect psychological distress in middle-aged and older adults according to their work status. This study aimed to examine and clarify the relationship between sleep efficiency and psychological distress in middle-aged and older Japanese stratified by work and sex. A cross-sectional study was performed among community dwellers aged 40–90 years living in Shika-machi, Ishikawa, Japan, between January 2018 and April 2020. Psychological distress was assessed utilizing the Kessler 6 scale (K6), a psychological distress scale. Sleep efficiency was measured using actigraphy (MTI-220, ACOS Co., Ltd., Nagano, Japan) that includes the sleep index, and analyses were stratified by work status and sex. A multiple logistic regression analysis was conducted setting the high K6 group as an objective variable. A total of 360 middle-aged and older adults (women = 54.4%; mean age = 63.09 ± 10.48 years) were included in this study. Psychological distress, adjusted for confounders, was associated with low sleep efficiency (β = -0.060, p = 0.013) only among working women. We found no evidence of a relationship between other indicators of psychological distress in men with or without work and women without work. These results reveal a relationship between psychological distress and sleep efficiency among middle-aged and older working women, suggesting that work and poor sleep efficiency may be associated with greater psychological distress. Future studies should examine the relationship between psychological distress and sleep efficiency in women middle-aged and older using longitudinal studies that consider work-related effects.