REM Sleep Linked to Lower Risk of Dementia, Parkinson's, and Other Diseases

Greater amounts of rapid eye movement (REM) sleep were associated with a dramatically lower risk of 83 diseases, including dementia, Parkinson's disease, and heart failure, according to a new study.

Researchers analyzed data from over 95,000 adults who wore wrist accelerometers for seven consecutive days and nights. Using deep-learning algorithms, they examined various sleep metrics, including REM sleep, deep sleep, light sleep, total sleep duration, wakefulness after sleep onset, and sleep irregularity. This data was then correlated with health records over an average follow-up period of nearly nine years.

The study, published in PLOS Medicine, found that increased REM sleep was linked to a 46% lower risk of dementia and an 80% lower relative risk of Parkinson's disease. Heart failure risk was reduced by 26% with more REM sleep.

Furthermore, greater amounts of deep sleep were associated with a lower risk of seven conditions, including type 2 diabetes and major depressive disorder. A total sleep duration of six to eight hours per night was identified as the "sweet spot," correlating with the lowest risk for 69 diseases. Conversely, sleeping fewer than five hours per night was linked to an increased risk of 37 health conditions.

Night-to-night sleep irregularity and increased wakefulness during the night were associated with higher risks of conditions such as anxiety and substance use disorders.

Experts noted that while the study highlights a strong association, it cannot definitively prove that increasing REM or deep sleep directly prevents these diseases, as the relationship between sleep and health is complex. Disrupted sleep can sometimes be an early indicator of an underlying health issue, rather than solely a cause.

"Conditions such as Parkinson’s disease, dementia and heart failure can begin affecting sleep years before they are diagnosed," Dr. Chelsie Rohrscheib, head sleep expert at Wesper, told Fox News Digital. "At the same time, poor sleep may contribute to disease progression, so the relationship likely works both ways."

The study's authors acknowledged limitations, including its observational nature, the use of wrist-worn devices for sleep measurement which are less accurate than clinical studies, and the potential for unmeasured factors like medications to influence sleep. The study population, drawn from the UK Biobank, was also noted as being less diverse.

To promote better sleep, experts recommend adhering to good sleep hygiene practices, such as maintaining a consistent sleep schedule, creating a dark, cool, and quiet sleep environment, and avoiding substances like alcohol and caffeine before bed. For individuals with sleep pathologies like sleep apnea, treating these conditions can optimize REM sleep. Waking up feeling refreshed and not experiencing daytime sleepiness are key indicators of sufficient sleep quality, according to experts.