Most people do not use heating systems during nocturnal sleep in their bedrooms during the cold season in Japan; instead, they like to use extra blankets and quilts for sleeping. To investigate the effect of low air temperature (Ta) on sleep and thermoregulation when sleeping with bedding, 12 healthy young men participated in sleep experiments over three non-consecutive nights. The experimental conditions were at a Ta of 3 °C, 10 °C and 17 °C, with a relative humidity (Rh) of 50% and an air velocity of <0.2 m/s in the climatic chambers. The 4.3-clo bedding consisted of cotton sheets, an acrylic blanket, a down-filled quilt and a futon mattress. The average sleep efficiency index (SEI) remained >94% for each of the three Tas, and no disturbances were found by Ta in the sleep parameters, although the duration of rapid eye movement (REM) sleep showed variations at 3 °C. The skin temperature (Ts) of the forehead decreased in proportion to Ta and remained stable. The decreasing rate in rectal temperature (Tre), Ts of forehead and thigh during sleep were significantly greater at 3 °C than at 10 °C and 17 °C. The innermost microclimate temperature (Tmicro) made by the bedding did not correlate with the Tre. The young men were significantly more dissatisfied with 3 °C in the sleep quality evaluation. （日本人の多くは、冬季、睡眠時に部屋の暖房でなく、布団等の寝具を増やすことで対応している。本研究では、若年健常者12人を対象として、人工気候室内で3 °C、10 °C、17 °Cの、計3夜の睡眠時生理応答を検討した。睡眠ポリグラフィによる睡眠構築では条件間の差異は無く、睡眠効率は94%を超える値を示した。前頭部の皮膚温は、室温とともに低値を示し、睡眠中の直腸温、前頭部の皮膚温、および大腿部の皮膚温の低下率は、3℃の条件で他の2条件よりも顕著であった。睡眠の主観評価では、3℃の条件が最も満足度が低かった。）
8(6),76, 2018; https://doi.org/10.3390/buildings8060076
Tsuzuki K, Okamoto-Mizuno K, Mizuno K
