REM and deep sleep, not just total sleep time, associated with disease risk https://medicalxpress.com/news/2026-09-rem-deep-total-disease.html Accelerometer-derived real-world sleep stages and risk of incident diseases https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005213 Greater REM sleep was associated with a lower risk of heart failure and dementia