Effects of Bed Mattress and Pad Material on Initial Stages of Sleep under Mild Cold Exposure

Abstract

  The effects of bed mattress and pad material on initial stages of sleep under mild cold exposure were investigated. Nine healthy male subjects slept from 13:30 to 15:30 on a spring mattress with a polyester bed pad (S) and a camel hair mattress with a camel hair bed pad (C). Ambient temperature and relative humidity were maintained at 15℃ and 60％, respectively. Polysomnography recordings, skin temperature, microclimate, bed climate, and subjective sensations were obtained. The sleep efficiency index, total sleep time, and amount of rapid eye movement sleep (REM) significantly increased in C compared with S, while wakefulness decreased in C compared with S. No significant differences were observed in skin temperature. The microclimate temperature of the foot area significantly increased in C compared with that of S in the initial and later phases of sleep. The bed climate temperature of the waist area significantly increased in C compared with that in S in the later segment of sleep. The subjective thermal sensation of the foot was significantly warmer in C than it was in S. These results suggest that bed mattress and pad properties can decrease wakefulness and increase REM in mild cold exposure by increasing the bed climate temperature of the foot area and the sensation of warmth in the foot.