Mean skin temperature estimated from 3 measuring points can predict sleeping thermal sensation

Sensory input from the skin appears to be of crucial importance in the regulation of sleep but there has been limited research on human skin temperature during sleep. The present study was undertaken to validate calculation of the mean skin temperature (MST) of sleeping subjects from measurements at only three locations: forehead, chest, and foot, by means of an analysis of skin temperature data obtained from four human experiments that investigated the effects of thermal environment on the sleep quality and thermal comfort of a total of 64 sleeping subjects. The results show that skin temperatures were more evenly distributed across the body surface of sleeping subjects than they are when subjects are awake. The skin temperature of the forehead was highly correlated with thermal sensation in long-term measurements. MST values calculated using the three-point method were found to predict thermal sensation while sleeping better than those calculated using the normally accepted Hardy and Dubois's seven-point method. The validity, convenience and reliability of this approach, which also causes less sleep disturbance, makes it a suitable choice for obtaining estimates of mean skin temperature in sleep studies.