Spending more time in rapid eye movement sleep and deep sleep is associated with a lower risk of dozens of chronic conditions, including dementia, Parkinson’s disease, and type 2 diabetes, according to a large study of 95,559 adults published in PLOS Medicine.
UK Biobank Sleep Study Tracks 95,559 Adults Over Nine Years
Researchers analyzed sleep patterns from wrist accelerometers worn by 95,559 UK Biobank participants in middle and older age. Instead of relying solely on questionnaires, scientists used data from the wrist-worn devices alongside a deep-learning system called SleepNet to estimate REM sleep, light sleep, and deep sleep. Participants were then followed for a median of almost nine years to track health outcomes.
The international study was led by Capital Medical University in China. The research examined links between sleep patterns and more than 1,000 different diseases, identifying 156 associations between sleep patterns and the later development of health conditions.
REM Sleep Tied to Lower Risk of 83 Chronic Diseases
Greater amounts of REM sleep—the stage when most dreaming occurs—were associated with a lower risk of 83 chronic diseases. Every 47-minute increase in REM sleep was associated with substantial protection against those conditions. In particular, the study found that adequate REM sleep was connected to a 26% decreased risk of heart failure, a 46% decreased risk of dementia, and an 80% decreased risk of Parkinson’s disease.
REM sleep usually begins about 90 minutes after falling asleep and makes up about 20 to 25 percent of sleep. Scientists noted that REM sleep can be particularly curtailed by waking up too early, because its durations increase during the latter half of the night.
Deep Sleep Correlates With Reduced Type 2 Diabetes Risk
More deep sleep, also known as N3 sleep, was associated with a lower risk of seven conditions, including type 2 diabetes and major depressive disorder. While the findings highlight the value of deep sleep, researchers emphasized that the observational nature of the work does not prove that getting an extra hour of deep sleep will prevent diabetes.
The findings align with broader scientific understanding connecting good-quality rest to improved physical and mental health outcomes. However, sleep specialist Dr. Erin Creighton noted that sleep apnea can interfere with restorative sleep and break up sleep, leading to fragmentation even when a person spends enough hours in bed.
Optimal Sleep Duration Ranges From Six to Eight Hours
Sleep duration showed a striking pattern across 69 health outcomes, where the lowest risk tended to fall within a window of around six to eight hours a night. Those adults getting under five hours of sleep per night seemed to be the most susceptible group, seeing a significant increase in the risk of developing 37 different diseases.
Conversely, irregular sleep schedules and frequent nighttime awakenings were linked to a higher risk of anxiety and substance use disorders. The pressure to monitor and perfect sleep scores using wearable trackers can sometimes trigger anxiety, a phenomenon researchers call orthosomnia.
Common Questions About Sleep Stages and Disease Risk
Does wearing a fitness tracker give an accurate deep sleep score?
No. The sleep stages in the UK Biobank study were estimated from wrist movement using an algorithm rather than measured directly using a clinical overnight sleep study. Consumers have no reason to obsess over the deep sleep number produced by a consumer smartwatch, as those estimates are not a diabetes diagnostic test.
What are the signs of poor sleep quality despite getting enough hours?
According to sleep specialist Dr. Erin Creighton, signs include snoring, choking, coughing or gasping during sleep, or waking up not feeling refreshed or feeling like they are “dragging through the day” despite spending seven to eight hours in bed.
When should someone consult a general practitioner about sleep?
People who regularly sleep very little, wake repeatedly, snore heavily or feel exhausted despite spending enough time in bed should discuss these symptoms with a GP rather than simply accepting poor sleep as normal.
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