Effects of environmental temperature mimicking circadian rhythms on thermal comfort and sleep quality

Sleep is closely linked to human health, and the thermal environment plays a significant role in influencing sleep quality. This study investigates the effects of circadian rhythm-mimicking dynamic thermal environments on sleep quality and thermal comfort. Considering seasonal differences, two control conditions were established: a winter condition with a baseline temperature of 21 °C and a summer condition with a baseline temperature of 26 °C. Specifically, the winter experimental condition was designed with a temperature profile of 21–18–21 °C, while the summer condition followed a 28–26–28 °C profile. Ten participants were recruited for the sleep experiments, during which portable EEG devices were utilized to monitor sleep quality. Additionally, continuous skin temperature measurements were recorded at multiple body sites throughout the night to assess thermal regulation. Subjective thermal sensations and sleep quality were assessed using questionnaires administered before and after each experimental night. The experimental results revealed that, compared to a conventional winter environment, the dynamic thermal environment significantly improved sleep quality by increasing the proportion of deep sleep duration. No significant differences in sleep quality were observed under the summer conditions. Through discussion and analysis of thermoregulatory parameters significantly associated with sleep latency, this study attempts to elucidate the mechanism by which environmental control can shorten sleep latency. The findings provide valuable insights into the relationship between dynamic thermal environments, thermal comfort, and sleep quality, offering potential strategies for optimizing sleep environments.