The aim of this study was to investigate any effects of electric blanket on sleep stages and body temperature. Nine male subjects slept under two conditions: using the electric blanket (HB); and not using the electric blanket (C). The ambient condition was controlled at 3 degrees C relative humidity 50-80%. Electroencephalography, electrooculography (EOG) and electromyography, rectal temperature, skin temperature and microclimate temperature and humidity were recorded continuously through the night. Body weight was measured before and after sleep. The amount of stage 1 and number of stage 1 and rapid eye movement sleep decreased in HB compared to C. No significant difference was observed in other sleep stages. Rectal temperature was higher in HB compared to C. The thigh, leg and foot skin temperature was higher in HB than C. The microclimate temperature of the foot area was higher in HB compared to C. No significant difference was observed in whole body sweat loss between the conditions. These results suggest that use of an electric blanket under low ambient temperature may decrease cold stress to support sleep stability and thermoregulation during sleep.