Study links REM sleep to 25% lower risk of 83 diseases

Scientists have found that people who spend more time in rapid‑eye‑movement (REM) sleep are at lower risk of 83 different diseases, including dementia, heart failure and Parkinson’s disease, according to a new study published in the journal *Sleep* that tracked over 95,000 adults for up to 12 years. The research, led by Dr. Maria Gomez of the University of Michigan, used data from wearable sleep trackers and medical records to quantify how much REM and deep (slow‑wave) sleep participants received each night. Those with the highest REM percentages were 25 % less likely to develop any of the 83 conditions, while those with more deep sleep had a 15 % lower risk of type 2 diabetes and major depression.

The study comes as sleep science has moved beyond the simple “eight‑hour rule” to a more nuanced view of sleep architecture. REM sleep, which occurs in cycles after the first hour of sleep, is thought to consolidate emotional memories and regulate brain chemistry. Deep sleep, on the other hand, is associated with physical restoration and metabolic regulation. Prior research has linked short sleep duration to obesity and cardiovascular disease, but few large‑scale studies have dissected the protective effects of each sleep stage across such a wide spectrum of illnesses. By controlling for age, sex, body mass index and lifestyle factors, the researchers aimed to isolate the specific contribution of REM and deep sleep to disease risk.

The data showed that participants in the top quartile of REM sleep—averaging 20 % of total sleep time—had a 0.85 hazard ratio for developing dementia compared to those in the lowest quartile. Similarly, the top deep‑sleep group had a hazard ratio of 0.85 for type 2 diabetes. The authors caution that the study is observational, so causality cannot be proven, but the consistency of the associations across many diseases suggests a real biological link. The team also noted that people who reported good sleep hygiene—consistent bedtimes, reduced screen use before bed, and regular exercise—tended to have higher REM percentages, hinting at modifiable risk factors.

If these findings hold up in future trials, clinicians may begin to recommend targeted sleep interventions as part of disease prevention strategies. Public health agencies could incorporate sleep‑stage monitoring into routine health checks, and wearable‑device companies might develop algorithms to help users optimize REM and deep sleep. The authors plan to follow up with a randomized controlled trial that will test whether boosting REM sleep through behavioral or pharmacologic means can reduce the incidence of specific diseases, such as Parkinson’s and heart failure, over the next decade.