A STUDY TO EXAMINE THE THERMAL ENVIRONMENT ON SLEEP AND SUBJECTIVE SENSATIONS IN SHELTER-ANALOGUE SETTINGS IN WINTER

 In recent years, many large-scale disasters have occurred and life in an evacuation shelter has been the subject of some focus. However, with these facilities an insufficient thermal environment is assumed, which is thought to have an adverse effect on the health of evacuated people. In previous studies, environmental factors were clarified. However, there's no research to elucidate upon the influence on the human body when a person is sleeping in a shelter. Also, until now, research on sleep in summer has been actively conducted, but in winter sleep, the actual state of sleep in a low temperature environment hasn`t been examined due to the influence of bedding etc. Therefore, sleep was investigated in shelter-analogue settings in a gymnasium in our previous study (K. Mochizuki, 2018). In this research, we aimed to examine sleep in shelter-analogue settings in winter to determine the subjective sensation in evacuation shelters. So two bedding conditions were chosen: a pair of futons and four sheets of blankets for emergency. The insulation of the beddings and clothing were measured using a manikin in a climatic chamber. One night the subject used a pair of futons (3.1 clo : Futon) and on the other the subject used the emergency supplies of four blankets (1.3 clo : Blankets) and a set of portable partitions. Also the subjects slept with their own clothing such as a T-shirts, sweatshirts, hoodies, underpants, sweatpants, pants, and two pairs of socks (0.76 clo) during the sleep. During the night, air temperature, humidity and air velocity were measured in the area around the sleeping subjects. Sleep parameters were measured by actigraphy, where the microclimate temperature of the subjects were continuously measured and recorded during the sleeping period. The subjects were requested to respond to three questionnaires: before sleep, after sleep, and retrospective sensation during sleep. The questionnaire consisted of thermal comfort, sleep quality, subjective symptom, and fatigue. Twelve young healthy students took part in the sleep study of two nights for seven hours from midnight to 7 AM in the gymnasium.<br> There were no significant differences in sleep efficiency index, sleep onset latency, total sleep time and total wake time between the Blankets and the Futon. However, numbers of wake epoch and sleep epoch were significantly greater using Blankets than that using the Futon. As a result, length of sleep epoch was significantly shorter using Blankets than that using the Futon. This result means that sleep was disturbed when using Blankets. The subjects felt more coldness on their head and peripheral parts of the body using the Blankets than the Futon during sleep. Moreover, fatigue was felt more on the lower back and lower extremities from using the Blankets than the Futon after sleep. When the relationships between local skin temperature and local thermal sensation were examined, foot skin temperature had a good correlation with foot thermal sensation after and during sleep. The subjective sleep evaluations by OSA questionnaire were compared between the two conditions. The standardized scores of OSA were less than 50 except when subjects were having dreams, which means a worse sleep quality evaluated by subjective sensations. Significant differences were found on the sleepiness, sleep onset and maintenance of sleep, recovery, and the length of sleep period, with which the scores were higher using Futon than using Blankets. However, the sleep efficiency index and subjective sleep evaluation by OSA questionnaire did not reveal any good correlationship. These results show that emergency supplies should be examined for their suitability to provide comfortable and healthy sleep in shelter-analogue settings.