Sleep is recognized as a phenomenon controlled by the circadian rhythms. It is generally believed that sleep is important for stabilizing the energy, supporting healthy immune system of human body, besides, it is beneficial for brain plasticity and mental health [1,2]. The thermal environment while sleeping are perceived by human beings both cutaneously stimulated and emotionally provoked. A preferable thermal environment should be within the thermal regulation range of human body and evoke the best thermal sensation. With regard to the thermal environment for sleeping during night
Recently, air-conditioner use has become a heat stroke countermeasure. Studies of air-conditioner use and sleep quality have been conducted. Kubo et al.[1] conducted a questionnaire survey designed to evaluate thermal environment changes from airconditioner use during sleep. Results show that air-conditioner use during sleep affects thermal comfort when waking up. Ishimaru et al.[2] surveyed thermal environments during sleep. They reported that air-conditioner use causes waking up during sleep by a timer function.
Sakane et al.[3] to assess parameters of living environments, air-conditioner use, and sleep quality. Results revealed that the sleep quality of full time workers is affected by ‘residential heating and cooling performance’, ‘solar heat from windows’, and the air-conditioner use frequency during the day.
Current thermal comfort theories and standards are mainly concerned with people in waking state. The effects of air temperature on sleep quality and thermal comfort of sleeping people were investigated in this study by experimenting on human subjects by subjective questionnaires performed in the morning as well as electroencephalogram (EEG) signals, which were continuously recorded during the all-night sleep period. Subjective assessments on thermal comfort were performed both before and after sleep.
they reported poorer subjective sleep quality in such conditions. The returned subjective questionnaires on thermal comfort from subjects reflected that the thermal comfort temperature was higher in sleep compared with that in waking state. Their skin temperatures were increased with air temperature and fluctuated during the sleeping period. In view of the distinctive requirements from waking people, it makes sense to study the thermal comfort of sleeping people. The results also have practical implications on energy savings in bedrooms.