People who spend more time in REM, or dream, sleep face a measurably lower risk of developing dozens of diseases later in life, according to a large study published this month that tracked sleep patterns using ordinary wrist-worn fitness trackers.
Researchers analyzed data from 95,559 participants in the UK Biobank who wore accelerometers continuously for seven days and nights. A deep-learning model estimated how much time each person spent in REM sleep, deep sleep and light sleep, along with total sleep duration and how often their sleep was interrupted. Health records were then tracked for a median of 8.9 years to see which of more than 1,000 disease outcomes correlated with those sleep patterns, according to the study published in PLOS Medicine.
More REM sleep was associated with a lower risk of 83 separate diseases. The strongest associations included heart failure, dementia and Parkinson's disease, with participants who logged more REM sleep showing substantially reduced risk for each, according to findings summarized by Medical Xpress. Greater deep sleep was linked to lower odds of seven other conditions, including type 2 diabetes and major depressive disorder. Across nearly all conditions studied, people who slept between six and eight hours a night had the lowest overall disease risk, while those sleeping less than five hours faced higher risk across 37 conditions.
The researchers noted that irregular sleep schedules and more time spent awake after initially falling asleep were themselves linked to higher risk for conditions including anxiety and substance use disorders, suggesting consistency matters alongside sleep-stage composition.
Because the study is observational, the authors cautioned it cannot prove that more REM sleep directly prevents disease, only that the two are strongly correlated. Wrist accelerometers also cannot directly measure brain activity or eye movement, the hallmarks doctors use to define sleep stages in a lab, so the machine-learning estimates of REM and deep sleep are approximations rather than clinical measurements. Researchers said the findings nonetheless add to evidence that sleep quality, not just quantity, deserves more attention as a target for prevention.