Associations between summer bedroom temperatures and sleep quality in UK adults

Background There is limited field-based research on the role of indoor settings such as bedroom temperatures in adult sleep quality during summer, within temperate climates.Method An observational field study was conducted in summer 2024 with 59 adults (mean age: 29.3 yrs) in England, UK. Bedroom environmental parameters and sleep quality were measured subjectively (by validated questionnaires every night) and objectively (by HOBO MX CO2 logger and Actiwatch Spectrum Plus, continuously) over 7 days. Participants were asked to report their daily adaptive behaviours. Linear models were fitted to investigate the associations between bedroom air temperatures and sleep quality, adjusting for demographics, environmental factors, occupant adaptive and health behaviours, and health.Results Mean bedroom air temperature two hours before sleep (T.2h) and during sleep (T.mean) was respectively 24.8℃ (SD: 1.9) and 24.6℃ (SD: 1.9). Higher T.2h and T.mean was associated with 2.2% and 2.3% higher sleep efficiency; and 11.1% and 10.8% lower wake after sleep onset, respectively, after adjusting environmental factors, occupant adaptive and health behaviours, and health. No association was found between bedroom air temperatures and other sleep outcomes.Conclusions Within the range of nighttime bedroom temperatures of this study (17.9-30℃), higher temperatures at summer nights were associated with improved objectively-measured sleep efficiency and reduced objectively-measured wake after sleep onset.