Relationship between Sleep Disorder and Nighttime Outdoor Thermal Environment in the 23 Wards of Tokyo

Abstract

In the present study, relationships between resident sleep disorders and outdoor meteorological conditions were investigated using resident questionnaire data of the 23 wards of Tokyo in the 2007 summer. The daily sleep disorder rate (SLD) correlated with the nighttime outdoor minimum temperature (Tmin), and increased under exceeding Tmin of 25℃. The SLD and Tmin at a coastal region were lower than those of urban and inland regions in the 23 wards. The Heat Index (HI), which represents human feeling temperature, was preferred to be properly sleep disorder indicator of the thermal indices. Nights with widening gap between the HI and air temperature remarkably increased the SLD.