Nearly 95,000 people wore sleep trackers for years, and the data just revealed which sleep habits predict future disease.
Quick Take
- A UK Biobank study tracked sleep patterns in nearly 95,000 adults using wearable devices over an average of 6.8 years.
- Researchers linked those sleep patterns to 156 different disease outcomes in a study published in PLOS Medicine.
- More REM sleep and deep sleep were tied to lower risk of dozens of conditions, while irregular sleep raised risk.
- A separate study of nearly 7,000 people through the All of Us Research Program found the same basic pattern.
A Massive Wearable-Device Study Tracks Real Sleep, Not Guesses
Nearly 95,000 adults in the UK Biobank agreed to wear an actigraphy device that recorded their real sleep, night after night, for an average of 6.8 years. Instead of asking people to guess how they slept, researchers pulled hard data on sleep duration, timing, and disruption. That data was then matched against medical records to see which sleep habits showed up before disease struck.
The results, published in PLOS Medicine, connected variations in sleep to 156 separate disease outcomes. That is a far bigger net than most sleep studies cast. It let researchers compare sleep habits against everything from heart trouble to liver disease to mental health conditions, all inside one massive dataset.
REM and Deep Sleep Emerge as Protective Signals
Getting more REM sleep, the dream stage tied to memory and brain repair, was linked to lower risk of 83 different diseases. Deep sleep, the stage where the body repairs tissue and clears waste, was linked to lower risk of seven diseases. Neither finding proves that boosting these stages prevents illness, but the pattern held across a huge, real-world sample.
Total time spent awake in bed, known as wake after sleep onset, told a different story. More of it lined up with higher risk across a wide range of conditions. So did irregular sleep and disrupted rhythms, according to earlier coverage of the same body of research on irregular sleep patterns and chronic disease risk.
Irregular Sleep Carries Real Costs
Going to bed at wildly different times, or getting inconsistent amounts of sleep from night to night, showed up again and again as a red flag. Earlier reporting on this research area described poor sleep habits, including inconsistent bedtimes and disrupted rhythms, as tied to sharply higher risk for dozens of diseases, including conditions as serious as liver cirrhosis.
A Second Study Points the Same Direction
A separate analysis of nearly 6,785 adults through the National Institutes of Health’s All of Us Research Program used Fitbit-style wearables and reached a strikingly similar conclusion. Researchers there found REM sleep and deep sleep were inversely linked to atrial fibrillation, an irregular heartbeat condition. Sleep irregularity was tied to higher odds of obesity, high cholesterol, high blood pressure, major depression, and generalized anxiety disorder.
That study also found the relationship between total sleep time and risk was not a straight line. Both too little and too much sleep raised the odds of high blood pressure, depression, and anxiety, forming a J-shaped curve. That nuance matters, because it means the old advice to simply chase eight hours misses part of the picture.
What Doctors Say This Means for Ordinary People
Outside experts reviewing this research area have been careful about what it does and does not show. One expert reaction summarized it well, noting the results support sleep patterns as informative markers of future disease risk, but they do not prove that forcing more REM sleep or squeezing sleep into a fixed window will actually prevent disease.
Both studies point in the same direction using different populations, different devices, and different time frames. That kind of repeated signal, across nearly 100,000 combined participants, gives sleep trackers a stronger case for being more than a novelty gadget. For anyone tracking their own sleep, consistency and sleep quality may matter just as much as the number of hours logged each night.
Sources:
mindbodygreen.com, newsroom.clevelandclinic.org, sciencedaily.com, pmc.ncbi.nlm.nih.gov, stanfordhealthcare.org
