0101 Effects of Combined Hand and Foot Bathing on Heat Dissipation, Daytime Sleep Structure, and Gender Difference

Introduction Recent reports have highlighted the usefulness of partial body bathing, such as foot bathing, in nursing care and caregiving. However, many studies have focused on subjective evaluations; limited attention has been given to the objective evaluation and underlying mechanisms of these bathing practices. In this study, we investigated the relationships among heat dissipation due to combined hand and foot warm bathing, changes in body temperature, and objective sleep structures and examined potential sex-related differences in these parameters among healthy subjects. This study was approved by the Ethical Committee of Saitama Prefectural University. Methods Thirty healthy adults (14 men, 16 women; mean age, 21.47 ± 1.50 years) participated in a 2-day experiment involving a baseline condition (35ºC) and warm bath condition (40ºC) using a crossover design. Under each condition, the participants took a 15-minute hand and foot bath during the day, followed by 1-hour daytime polysomnography. We measured distal skin temperatures (hands and feet) and proximal skin temperatures (subclavian region and forehead) to determine the distal–proximal skin temperature gradient (DPG). We also measured the core body temperature. A registered polysomnographic technologist scored the sleep stages in 30-second epoch periods according to the Scoring Manual of the American Academy of Sleep Medicine. Results The DPG during bathing, after bathing, and during sleep was significantly higher in the warm bath than baseline condition. In addition, the duration of slow-wave sleep was longer in the warm bath condition, especially at 20 to 40 minutes after bedtime. With respect to sex-related differences, the DPG during the sleep period was significantly higher and the duration of slow-wave sleep in the warm bath condition was significantly longer in women than in men. There was no significant difference in the DPG between the baseline and warm bath conditions in men. Conclusion A 15-minute combined hand and foot warm bath promoted heat dissipation and increased the duration of slow-wave sleep. Heat dissipation was accelerated only in women, suggesting sex-related differences in heat dissipation during sleep, even under partial bathing conditions. In future research, we will examine the factors contributing to the sex-related differences found in this study. Support (if any)