Climate warming may undermine sleep duration and quality in repeated-measure study of 23 million records

The impact of rising ambient temperatures on sleep and its phases under climate change is becoming increasingly concerning but remains underexplored. Sleep, consisting of non-rapid eye movement and rapid eye movement phases, is crucial for health, and insufficient sleep in either phase could have significant implications. Based on sleep monitoring data of 23 million days from 214,445 participants across mainland China, we investigated how daily average temperature affected sleep. For each 10 °C increase in ambient temperature, the odds of sleep insufficiency increased by 20.1%, while total sleep duration decreased by 9.67 minutes, with deep sleep declining the most (by 2.82%). Projections under the unrestricted (SSP5-8.5) greenhouse gas emission scenario suggest that by the end of the century, sleep insufficiency could rise by 10.50%, with an annual loss of 33.28 hours of sleep per person. These findings highlight the potential of climate warming to exacerbate sleep deprivation and degrade sleep quality, especially for the elderly, women, individuals with obesity, and regions of South, Centre and East.