[Association of regularity of dinnertime and elapsed time from dinner to going to bed with subjective sleep quality among locally-living working-age men and women].

Objective This study aimed to clarify the relationship between the regularity of dinnertime, elapsed time between dinner and bedtime (elapsed time after dinner), and subjective sleep quality among locally-living working-age men and women.Methods Data from the DOSANCO Health Study conducted in 2015 in Suttsu-chou, Hokkaido, Japan, were used. Of the 2,638 residents aged ≥3 years, excluding nursing home residents, 773 aged 20-69 years and those who met the inclusion criteria were analyzed. The regularity of dinnertime was divided into two groups; "regular" and "irregular." Furthermore, the regular group was divided into five groups according to the time elapsed between dinner and bedtime; "≤2 h," "＞2 h, ≤3 h," "＞3 h, ≤4 h," "＞4 h, ≤5 h," and "＞5 h." Subjective sleep quality was assessed using the Japanese version of the Pittsburgh Sleep Quality Index, with a total score of ≥6 being "subjective poor sleep quality." Prevalence ratios (PR) and 95% confidence intervals (CI) were calculated by sex and age group (20-39, 40-59, and 60-69 years) using log-binomial regression analysis with SAS software (version 9.4; SAS Institute Inc.).Results The PR (95% CI) for subjective poor sleep quality was significantly higher in the irregular group (men; 1.71 [1.28-2.28], women; 1.50 [1.12-2.00]) than the regular group. Among the regular group, the PR (95% CI) for subjective poor sleep quality compared with the "＞3 h, ≤4 h" group as the reference was 1.81 (1.17-2.80) in the "＞5 h" group of women. The group with a longer elapsed time from dinner had higher subjective poor sleep quality in women, particularly in women aged 40-59 years.Conclusions Irregular dinnertimes or a lifestyle with a long elapsed time between dinner and bedtime, despite regular dinnertimes, may be associated with poor sleep quality.