Investigating the effect of bedroom temperatures on thermal comfort and sleep quality in natural settings

Adequate sleep is crucial to human health and well-being and elevated night-time temperatures can degrade sleep quality. European countries with temperate climates use temperature thresholds between 25°C and 28°C to identify homes that are overheated. The current UK bedroom threshold temperature of 26°C is based on one small study which is now over 45 years old.; a new bedroom overheating criterion has recently been proposed.

Internationally, there have been very few studies of bedroom temperatures and their influence on thermal comfort and sleep quality for people sleeping in their natural environment. Early results from one such study, the Homes Heat Health project are reported. Data were collected during the summer of 2023 from 25 participants living in apartments (flats) in East London. The participants were healthy with no pre-existing medical conditions that would affect their sleep. A survey recorded the geometry and thermal characteristics of bedrooms, sensors recorded bedroom temperatures and humidity, actigraphy was used to measure night-time sleep patterns, and a phone app captured participants’ nightly comfort and sleep quality.

The nighttime bedroom temperatures and self-reports of thermal comfort and sleep quality during a week of hot weather were compared with reports made during a week of typical summer weather. Mean and maximum nighttime bedroom temperatures were significantly warmer during the hot week (p<0.001). Compared to the typical week, there was a significant reduction in reported sleep quality (p<0.05) and thermal comfort (p<0.001) and an increase in sleep disturbance (p< 0.001).