The effects of bed cooling on sleep quality and sleep thermal comfort in overheated bedrooms

• The first UK study of a bed cooling system in overheated bedrooms (n =17). • Bed cooling increased mean Total Sleep Time by 19 minutes in overheated bedroom. • Bed cooling reduced mean Sleep Onset Latency by 10 minutes in overheated bedroom. • Bed cooling improved self-rated mean sleep quality from 2.8 to 3.7 (1–5 scale). • Significant improvement in thermal comfort, sensation, acceptability and preference (p < 0.05). Elevated night-time temperatures in bedrooms on hot summer nights impairs sleep quality and sleep thermal comfort. Passive and low energy night-time cooling strategies can enhance individuals’ comfort without relying on air conditioning. This study evaluates the impact of a low-energy, water-based cooling mattress topper on sleep thermal comfort and quality in healthy adults sleeping in overheated UK bedrooms. Seventeen participants took part in repeated-measures controlled-bedroom experiments consisting of three stages: (1) baseline sleep in their own bedrooms under normal summer conditions, (2) sleep on a standard bedding system in a bedroom controlled at 30°C, and (3) sleep in the same overheated bedroom with the cooling mattress topper. Objective sleep metrics were recorded using wrist actigraphy, while subjective thermal comfort and sleep quality were assessed using validated questionnaires. The cooling mattress topper was found to significantly improve sleep thermal comfort metrics (p < 0.05) with large effect sizes (r = 0.71 to 0.93). Substantial improvements in perceived sleep quality and a reduction in time spent awake were also reported. Actigraphy data showed that use of bed cooling restored total sleep time to baseline levels and reduced Sleep Onset Latency by ten minutes compared to using standard bedding. The findings suggest that targeted bed cooling is an effective, low-energy solution for mitigating sleep disruption in overheated bedrooms, and for mitigating the effects of increasing summertime temperatures in UK homes. There is an urgent need for sleep-specific overheating standards for UK homes.