Cross-sectional Internet-based survey of Japanese permanent daytime workers' sleep and daily rest periods.

OBJECTIVES

This study aimed to describe the sleep quantity, sleep quality, and daily rest periods (DRPs) of Japanese permanent daytime workers.

METHODS

Information about the usual DRP, sleep quantity, and sleep quality (Japanese version of the Pittsburgh Sleep Quality Index: PSQI-J) of 3,867 permanent daytime workers in Japan was gathered through an Internet-based survey. This information was analyzed and divided into the following eight DRP groups: <10, 10, 11, 12, 13, 14, 15, and ≥16 h.

RESULTS

The sleep durations for workers in the <10, 10, 11, 12, 13, 14, 15, and ≥16 h DRP groups were found to be 5.3, 5.9, 6.1, 6.3, 6.5, 6.7, 6.7, and 6.9 h, respectively. The trend analysis revealed a significant linear trend as the shorter the DRP, the shorter was the sleep duration. The PSQI-J scores for the <10, 10, 11, 12, 13, 14, 15, and ≥16 h DRP groups were 7.1, 6.7, 6.7, 6.3, 6.0 (5.999), 5.6, 5.2, and 5.2, respectively. The trend analysis revealed a significant linear trend as the shorter the DRP, the lower was the sleep quality.

CONCLUSIONS

This study described sleep quantity, sleep quality, and DRP in Japanese daytime workers. It was found that a shorter DRP was associated with poorer sleep quantity as well as quality.