Soomin Lee, Heri Sanjaya Kadek, Hiroko Fujimura, Yoshihiro Shimomura and Tetsuo Katsuura
Aims: In Japan, although evening bathing as a means of both cleaning and relaxation has been a wellestablished custom from ancient times, the prevalence of morning baths has increased in Japan in recent years. The effects of morning bathing on human sleep quality have not yet been revealed. Thus, we aimed to clarify the effects different bathing method on human sleep quality.
Methods: The first night, the subject entered the laboratory at 19:00 and went to bed at 24:00. On the second day, the subject got up at 07:00 and either showered, took a mist sauna, or did not bathe, between 07:10 and 07:20. Each hour after that, the subject completed an alpha attenuation test (AAT), Kwansei-Gakuin sleeping scale (KSS) test and subjective evaluations from 09:00 to 17:00. We measured the melatonin concentrations at 22:30, 23:00, 23:30, and 24:00 of the second day. On the third day, the subject got up at 07:00 and finished at 07:30. Key finding: We found that the melatonin concentrations after morning showering were significantly lower than those after no bathing at 23:00, 23:30, and 24:00. In addition, the selections of “coziness” on the subjective evaluation after the mist sauna were significantly higher than those after no bathing at 7:20. The selection of “fatigue” after the mist sauna bathing was significantly lower than that after showering during the task period at 14:00.
Significance: Our findings indicate that the morning mist sauna bathing method produced more good feelings and prevented fatigue compared to other bathing methods.
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