REM and deep sleep, not just total sleep time, associated with disease risk
Greater amounts of REM and deep sleep were associated with lower risks of dozens of diseases, and less than 5 hours of total sleep was associated with high disease risks, according to a new study published Sept. 17 in the journal PLOS Medicine by Shengzhi Sun of Capital Medical University, China, and colleagues.
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Sleep quantity and quality are priorities of China's National Health Commission and a focus in China more broadly. The most recent 2026 China Sleep Health White Paper finds that while the average Chinese person surveyed sleeps 6.97 hours per night, 23% sleep less than 6 hours per night. The same report notes that only 26% of respondents reported a consistent sleep schedule and that sleep disturbances have increased over time. Understanding how sleep patterns are linked to disease risk is therefore highly relevant to Chinese citizens.
There remains limited understanding of how sleep stages and other real-world sleep patterns relate to health outcomes. In part, that is because self-reported sleep measures often show poor correlation with objective assessments, making it difficult to capture real-world sleep patterns.
In the new study, researchers analyzed data from 95,559 UK Biobank participants who wore wrist accelerometers for seven consecutive days and nights. The researchers used a deep-learning algorithm to calculate sleep stages (REM, deep and light sleep), total sleep duration, wakefulness after sleep onset and night-to-night sleep irregularity. Participants were followed for a median of 8.9 years, and health records were available to test associations with more than 1,000 disease outcomes.