A Sleeptracker-AI study of over 1,750,000 nights of sleep confirms that bedroom air temperature directly affects sleep quality. On nights when bedroom temperature is cooler than usual, total sleep duration increases and a greater proportion of that sleep is spent in REM. Warmer nights produce the opposite effect.

The finding is consistent with published clinical research. The Sleep Foundation identifies approximately 65°F (18.3°C) as the optimal sleep temperature, with most physicians recommending a range of 60–67°F (15.6–19.4°C). A peer-reviewed study on bedroom temperature and ventilation found that for every 1K increase in bedroom operative temperature, sleep efficiency drops by 1.036% and REM sleep percentage falls by 1.647%. A separate climate research analysis establishes a robust link between atypical nightly temperatures and insufficient sleep — an effect largest in summer and most pronounced among lower-income individuals and the elderly.

The population-scale Sleeptracker-AI data and the published literature are in agreement: a cooler bedroom meaningfully improves both sleep duration and architecture.

Here are a few helpful links:

Climate change and sleep impact study (deviations from mean temperature are investigated)
https://www.science.org/doi/10.1126/sciadv.1601555

“Our analysis of historical data demonstrates a robust link between atypical nightly temperatures and insufficient sleep that is largest during the summer and among lower-income individuals and the elderly. Moreover, across both our city-level and geographic grid cell–level forecasts, we predict that every location in the United States may experience an increased incidence of insufficient sleep due to nighttime warming induced by future climate change.”

Another abstract that is interesting:

Associations of bedroom temperature and ventilation with sleep quality
https://www.tandfonline.com/doi/abs/10.1080/23744731.2020.1756664?src=recsys&journalCode=uhvc21

“Sleep efficiency (ratio of time asleep to time in bed) and rapid eye movement (REM) sleep (%) were both negatively correlated with bedroom operative temperature; as bedroom operative temperature increases by 1 K, the estimate of sleep efficiency and REM sleep percentage decrease by 1.036% and 1.647%, respectively.”