水野 一枝

BACKGROUND: We investigated the relationship between sleep, ambient climate, and bed climate in school-aged children during a one-night stay in a simulated shelter in a gymnasium to demonstrate the effect of ambient climate, and bed climate on sleep. METHODS: We obtained measurements during a one-night stay in a school gymnasium (C), days before C (BC), on the day after (A1), and on the second day after C (A2) in 13 healthy school-aged children during summer. Sleep was evaluated using an actigraph, and the temperature and humidity of the bedrooms in the participants' homes and in the gymnasium were monitored for 3 days before and after C. The bed climate of the chest and foot areas was measured for two nights before and after C. The participants were asked to report on their subjective sleep estimations and thermal sensations two nights before and after C. RESULTS: The ambient temperature in C was significantly higher than that in BC at the initial 180 min, while it significantly decreased compared to A1 and A2 in the last 100 min. The ambient humidity was significantly higher in both C and BC compared to A1 and A2. The sleep efficiency index decreased significantly in C (43±4.8%) compared to other conditions. Sleep time was significantly shorter in C than in other conditions during the initial 195 min. The increase in the bed climate temperature of the chest area in C was significantly delayed compared to that in the other conditions, around the initial 30 min after the lights were off. Subjective estimation revealed that in C, 85% of the participants were out of their sleeping bag at sleep onset, and their sleep was disturbed by heat (77%). CONCLUSIONS: Our study revealed that the disturbed sleep patterns observed with children in a simulated shelter may be related to a delayed increase in bed climate temperature in the chest area. This delayed increase could be related to the children not entering the sleeping bag and a delayed chest skin temperature increase during the sleep onset period.

【目的】SIDSの多い冬季に乳児と母親の寝室内照度,寝床内気候,睡眠の実態を比較し問題点を検討することを目的とした。【方法】生後2～3ヵ月の乳児と母親5組を対象に冬季に在宅で3夜,寝室内温湿度と照度,寝床内気候,アクチグラフによる睡眠を測定した。母親には睡眠日誌,寝具,寝衣の調査用紙の記載,起床時に寝床内温冷感,湿潤感の主観調査を実施した。【結果】就寝時の寝室内の照度は0.1±0.6lx,授乳時の最高照度は96.4lxであった。寝床内温湿度は,背部,足部ともに乳児が母親より有意に高かった(p<0.01)。睡眠変数は母子間で有意差はなかった。【結語】SIDS予防を含めた睡眠環境調整及び睡眠について養育者に情報提供や相談を行う必要性が示唆された。また,冬季において,乳児の寝床内温湿度は母親より高いことから,乳児の就寝時には発汗の有無の確認を推奨したいと考える。(著者抄録)

This study aimed to examine the sleep habits in pairs of Japanese high school students and their mothers in the summer and autumn. Nineteen pairs of high school students and their mothers participated in this study. Wrist actigraphy, subjective sleep evaluations, and bedroom environmental measurements (temperature, humidity, and light) were performed for a duration of one week. The results of a split-plot analysis of variance revealed no significant difference in the actigraphically evaluated time spent in bed (TIB) between the seasons and between the mothers and students. The TIB was approximately 6 h on weekdays, and significantly lengthened to approximately 7 h on weekends (p < 0.05). The average sleep efficiency values recorded were higher than 90%. The mothers showed significantly advanced sleep phases compared to those of the students (p < 0.05). In addition, the waking time on Monday morning was significantly correlated between the mothers and students in the summer and autumn (p < 0.05). A perceived sleep loss “almost every day” or “several times per week” was reported by approximately half of the mothers and students in each season. The students occasionally fell into nocturnal sleep with the room light turned on. These results suggest that sleep hygiene education considering life habit characteristics is required to ensure sufficient sleep time.