More REM Sleep Linked to Lower Risk of 83 Diseases: What a 95,000-Person Study Found
Updated: 2 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
A large study published in September 2026 in PLOS Medicine found that adults who got more REM sleep (the "dreaming" stage) had a lower risk of 83 different diseases over about nine years, including heart failure and dementia. People who slept less than five hours a night had higher risk of 37 conditions. The study shows a link, not proof that sleep stages cause these differences. (Luo et al., PLOS Medicine, 2026)
Key takeaways
Researchers tracked the sleep of 95,559 UK adults with a wrist device for one week, then followed their health for a median of 8.9 years.
About 48 more minutes of REM sleep was linked to lower risk of 83 diseases, including heart failure, atrial fibrillation and dementia.
More deep sleep was linked to lower risk of 7 conditions, including type 2 diabetes and depression.
For most conditions, the lowest-risk sleep duration was between 6 and 8 hours, and often close to 7–7.5 hours.
This is an observational study: it shows associations, not cause and effect.
What did the new sleep study find?
The study found that the type of sleep people got, not only the total hours, was tied to their future disease risk. More REM and deep sleep were linked to lower risk of many diseases. Broken, irregular or very short sleep was linked to higher risk of several conditions, including depression and anxiety.
The research team, from Capital Medical University and Peking University in China, used data from UK Biobank, a large health database of British volunteers. Participants (average age 56; 56% women) wore a wrist accelerometer, a small motion sensor like a fitness tracker, for seven days between 2013 and 2015. The researchers then checked hospital records for more than 1,000 different diseases over the following years. (PMC full text)
After a strict statistical correction for testing so many diseases, they found 156 significant links between sleep and disease.
What is REM sleep, and what is deep sleep?
REM (rapid eye movement) sleep is the stage when most vivid dreaming happens and the brain is highly active. Deep sleep (also called slow-wave or N3 sleep) is the stage when the body is hardest to wake. Light sleep (N1 and N2) is the lighter stage that makes up much of the night. A normal night cycles through all three several times.
In this study, the typical participant got about 82 minutes of REM sleep, 103 minutes of deep sleep and 193 minutes of light sleep a night (median values).
Which diseases were linked to REM sleep?
For every extra 48 minutes or so of REM sleep, the risk of 83 diseases across 12 body systems was lower. The strongest links were for heart and brain conditions, including heart failure, atrial fibrillation, coronary heart disease, dementia and Alzheimer's disease. These are associations, and the true effect of REM sleep could be smaller.
Here are some of the reported figures. A "hazard ratio" (HR) below 1.0 means lower risk. For example, 0.74 means about 26% lower risk.
Sleep measure (per ~48 min more, unless stated) | Condition | Hazard ratio (95% CI) |
|---|---|---|
More REM sleep | Heart failure | 0.74 (0.68–0.80) |
More REM sleep | Atrial fibrillation | 0.83 (0.79–0.86) |
More REM sleep | Ischemic (coronary) heart disease | 0.87 (0.83–0.92) |
More REM sleep | Dementias | 0.54 (0.47–0.62) |
More REM sleep | Alzheimer's disease | 0.69 (0.57–0.81) |
More deep sleep | Type 2 diabetes | 0.89 (0.85–0.93) |
More deep sleep | Major depression | 0.86 (0.82–0.91) |
More light sleep | Major depression | 1.31 (1.25–1.36) |
Less regular sleep (~93 min more night-to-night variation) | Anxiety disorders | 1.23 (1.16–1.31) |
Source: Luo et al., PLOS Medicine, 2026.
How many hours of sleep were linked to the lowest disease risk?
For 69 of the conditions studied, the lowest risk was seen between 6 and 8 hours of sleep a night. For type 2 diabetes it was about 7.3 hours, and for dementias about 7.5 hours. Sleeping under 5 hours was linked to higher risk of 37 conditions, including a roughly 2.6-fold higher dementia risk.
Sleeping more than 8 hours was linked to higher risk of only one condition in the main analysis: major depression (HR 1.60). That does not mean long sleep causes depression. Sleeping longer may be an early symptom of depression rather than a cause of it.
The researchers also noticed that people sleeping 6–8 hours had the highest share of REM sleep and the least broken, irregular sleep. That may help explain why this range looked best. (PLOS Medicine)
The authors concluded: "Maintaining 6–8 hours of sleep is associated with a more favorable sleep architecture and lower disease risk, offering insights for prevention and health promotion."
For everyday guidance, the US Centers for Disease Control and Prevention (CDC) recommends 7 or more hours for adults aged 18–60, 7–9 hours for ages 61–64 and 7–8 hours for people 65 and older. (CDC)
Does this prove that more REM sleep prevents disease?
No. This was an observational study, so it cannot prove that REM or deep sleep causes lower disease risk. Other factors could explain part of the link. Early, undiagnosed illness can also disturb sleep years before a diagnosis, which would make poor sleep look like a cause when it is really an early sign.
The authors checked for this. When they ignored diseases diagnosed in the first two years after sleep was measured, 95 of the 156 links remained. That means about 40% did not hold up, which suggests reverse causation explains part of the pattern.
Other important limits the researchers reported:
Sleep stages were estimated, not directly measured. A computer algorithm guessed sleep stages from wrist movement. It was trained against lab sleep tests (polysomnography), but its accuracy was only moderate.
Only one week of sleep was recorded, which may not reflect a person's usual sleep over years.
Diagnoses came from hospital records only, so milder conditions treated by family doctors were missed.
UK Biobank volunteers tend to be healthier and wealthier than average and are mostly of White European ancestry, so results may not apply equally to everyone.
The study was funded by Chinese government science grants, and the authors declared no competing interests.
Should I track my REM sleep with a smartwatch?
You don't need to. This study did not test consumer trackers or show that tracking improves health. Its own authors describe the sleep-stage estimates as movement-based rather than exact physiological measurements, and they differed on average from lab sleep tests. A tracker can show general trends but does not diagnose anything.
If you have ongoing trouble sleeping, loud snoring, gasping at night or heavy daytime sleepiness, see a doctor. A proper sleep assessment can check for conditions such as sleep apnea.
What can I do to improve my sleep?
The practical message is to protect regular, sufficient sleep. The CDC lists these habits to improve sleep quality (CDC):
Go to bed and get up at the same time every day, including weekends.
Keep your bedroom quiet, relaxing and at a cool temperature.
Turn off electronic devices at least 30 minutes before bedtime.
Avoid large meals and alcohol before bedtime.
Avoid caffeine in the afternoon or evening.
Exercise regularly and keep a healthy diet.
The first habit ties directly to this study: more night-to-night variation in sleep was linked to higher risk of anxiety and depression.
The bottom line
This large study adds to growing evidence that how you sleep may matter as much as how long you sleep. More REM and deep sleep, fewer awakenings and a regular schedule were all linked to lower risk of many diseases. It shows association, not proof. The safest takeaway matches long-standing advice: aim for about seven hours or more of regular, good-quality sleep.
Frequently asked questions
How much REM sleep is normal?
In this study of 95,559 adults (average age 56), the typical person got about 82 minutes of REM sleep a night, as estimated by a wrist device. Most people got between 59 and 107 minutes.
How much deep sleep do I need?
There is no single official target for deep sleep. In this study, participants typically got about 103 minutes a night, and about 48 more minutes was linked to lower risk of seven conditions, including type 2 diabetes and depression. Getting enough total sleep on a regular schedule is the most practical way to support healthy sleep stages.
Is sleeping 6 hours enough?
In this study, 6–8 hours was the reference range, and many conditions had their lowest risk closer to 7–7.5 hours. The CDC recommends 7 or more hours for adults aged 18–60. Consistently sleeping under 5 hours was linked to higher risk of 37 conditions, including dementia and heart failure.
Is too much sleep bad for you?
In this study, sleeping more than 8 hours was linked to higher risk of only one condition, major depression. Long sleep may be a symptom rather than a cause. If you regularly sleep much longer than usual or still feel exhausted, it is worth discussing with a doctor.
Can a fitness tracker measure REM sleep accurately?
Not precisely. The wrist-device method used in this study was trained against lab sleep tests but showed only moderate agreement, and its authors call the estimates movement-based rather than exact. Trackers can show general trends. If you are worried about your sleep, a doctor can arrange a proper sleep assessment.
Health information, not medical advice. This article is for general health information and education only. It is not personal medical advice and does not replace a consultation with a qualified healthcare professional. If you have concerns about your sleep or health, please speak to your doctor.
Sources
Luo J, Liu R, Yin J, Cao W, Sun S, Chen R. Accelerometer-derived real-world sleep stages and risk of incident diseases: A UK Biobank cohort study and phenome-wide association analysis. PLOS Medicine. 2026;23(9). doi:10.1371/journal.pmed.1005213. Link · PMC
Centers for Disease Control and Prevention. About Sleep. Link
About the author: Dr. Baraa Alnahhal, MD, is a medical doctor and the founder of Rinnit. Dr. Baraa Alnahhal reviews new medical research and translates it into clear, evidence-based health information for everyday readers.
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