The relationship of sleep complaints risk factors with sleep phase, quality, and quantity in Japanese workers.

Numerous studies have determined that lifestyle factors (smoking, drinking, snacking, etc.) and the bedroom environment can influence sleep. We developed a new sleep scale-the 3-Dimensional Sleep Scale (3DSS)-which measures three elements of sleep: phase, quality, and quantity. The purpose of this study is to determine which risk factors of sleep complaints are associated with these sleep elements. Data were obtained from 366 Japanese day workers (302 men and 64 women). Sleep condition was assessed with the 3DSS, and we also assessed various habits within 2 h of going to bed, including smoking, drinking, snacking, caffeine intake, mobile phone use, and working. We also asked about bedroom environmental conditions (noise, lighting, and temperature and humidity). Multivariate logistic regression analysis using the backward selection method (likelihood ratio) was used, with 3DSS scores as the outcome (i.e., over or under the cutoff). The results showed that smoking was associated with significantly greater odds ratio [2.71 (1.65-4.44)] of disordered sleep phase, while lighting as well as temperature and humidity led to greater odds [3.67 (1.55-8.68), 1.93 (1.20-3.11)] of poor sleep quality. Finally, only noise was significantly related to greater odds [1.98 (1.13-3.46)] of low sleep quantity. These findings indicated the various risk factors of sleep complaints could be associated with different sleep elements. This might help in the effective treatment of sleep complaints.