Abstract
Recently, a growing number in Japan are switching to taking baths in the morning (morning bathing). However, the effects of the morning bathing on human physiological functions and work efficiency have not yet been revealed. Then, we hypothesized that the effect of morning bathing on physiological functions would be different from those of night bathing. In this study, we measured the physiological functions and work efficiency during the day following the morning bathing (7:10–7:20) including showering, mist sauna bathing, and no bathing as a control. Ten male healthy young adults participated in this study as the subjects. We evaluated the rectal temperature (Tre), skin temperature (Tsk), heart rate (HR), heart rate variability (HRV), blood pressure (BP), the relative power density of the alpha wave (α-wave ratio) of electroencephalogram, alpha attenuation coefficient (AAC), and the error rate of the task performance. As a result, we found that the HR after the mist sauna bathing was significantly lower than those after no bathing rest 3 (11:00). Furthermore, we verified that the α-wave ratio of the Pz after the mist sauna bathing was significantly lower than those after no bathing during the task 6 (15:00). On the other hand, the α-wave ratio of the Pz after the mist sauna bathing was significantly higher than those after showering during the rest 3 (11:00). Tsk after the mist sauna bathing was higher than those after the showering at 9:00 and 15:00. In addition, the error rate of the task performance after the mist sauna bathing was lower than those after no bathing and showering at 14:00. This study concludes that a morning mist sauna is safe and maintains both skin temperature compared to other bathing methods. Moreover, it is presumed that the morning mist sauna bathing improves work efficiency comparing other bathing methods during the task period of the day following the morning bathing.
Highlights
It is a Japanese custom to bathe daily for cleanliness, warmth, and relaxation (Tochihara 1999)
We verified the effects of different methods of morning bathing on human physiological functions and work efficiency during the day
We found that heart rate (HR) during rest in the mist sauna condition was lower than that of the no bathing conditions at 11:00
Summary
It is a Japanese custom to bathe daily for cleanliness, warmth, and relaxation (Tochihara 1999). Bathing that involves washing grime from the body and face with soap while immersed in a hot bath can cause major changes to the physiological function of the skin (Berardesca et al 1995; Okuda et al 2002) and to thermoregulation (Hashiguchi et al 2002). Many previous studies have reported the effects of bathing circumstances, method, style, postures, etc., on human physiological and psychological functions. Miwa et al (1994, 1998, 1999), concluded that bathing can induce remarkable changes in the cardiovascular system by increasing core temperature through immersion in hot water (40 °C) for more than 10 min. Mean skin temperature (Tsk) during sink bathing was significantly higher than during standing or seated showers. In terms of style of bathing, Johnston et al (1981) found higher oxygen consumption and
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