A large observational analysis of UK Biobank data examined relationships between objectively measured sleep and later disease risk. The study included 95,559 adults with a mean age of 56.2 years. Participants wore wrist accelerometers for one week to estimate sleep duration, time spent in sleep stages (including REM and deep sleep), and measures of sleep irregularity. After the baseline week of measurement, participants were followed for a median of 8.9 years until the onset of a health condition or death. The study was published in PLOS Medicine.
The article summarizes general scientific perspectives on sleep: it is evolutionarily conserved and is believed to serve multiple vital functions. Proposed roles include memory consolidation, clearance of metabolic byproducts from the brain, support for immune function, tissue repair, and allowing the gut microbiome to rest. Good-quality sleep is described as important for long-term health.
Using accelerometer-derived estimates of time in sleep stages, the investigators found distinct associations by stage. Notably, greater time in REM (dream) sleep at baseline was associated with a lower risk of 83 health conditions. Examples of conditions linked to greater REM time with reduced risk include heart failure, hypertension, atrial fibrillation, ischemic heart disease, Parkinsonism, multiple sclerosis, and dementias.
Greater amounts of deep sleep were associated with lower risk for seven conditions, among them type 2 diabetes, major depressive disorder, sleep apnea, and Parkinson’s disease. In contrast, spending more time in light sleep—a marker of poorer sleep quality—was associated with increased risk for some conditions (for example, major depressive disorder) but lower risk for others (for example, heart failure and cellulitis) in this analysis.
The researchers assessed sleep irregularity and a fragmentation metric called wakefulness after sleep onset (WASO), which quantifies time awake after initially falling asleep. A higher WASO score was associated with increased risk of six conditions, including psychoactive substance dependence, alcohol abuse, and osteoarthritis. Irregular sleep patterns were associated with higher risk of abdominal pain, anxiety, and major depressive disorder.
Longer overall sleep duration in this cohort was associated with a reduced risk of about 50 conditions, including protein–calorie malnutrition, acidosis, and type 2 diabetes. Based on their analyses, the authors concluded that sleeping 6–8 hours was associated with the lowest overall risk of health problems in this sample—slightly different from some commonly cited guidelines that recommend 7–9 hours.
The authors emphasize that the study is observational and that some associations may reflect reverse causation rather than causal effects of sleep on disease risk. For example, disrupted sleep is a common symptom of depression, so an observed association between poor sleep and depression could arise because depression impairs sleep rather than sleep driving incident depression. The analysis used objective accelerometer measures rather than self-report, which permits evaluation of sleep stages and fragmentation, but causality cannot be established from these data alone.
The article includes practical recommendations from sleep clinicians and scientists who were not involved in the study:
Keep a consistent wake-up time every day, including weekends, to stabilize sleep–wake patterns and support circadian organization. Morning daylight soon after rising can help solidify the routine.
Avoid persistently trying to fall asleep while anxious in bed. If unable to sleep, step away from bed for 15–20 minutes, go to a quiet dim room and do a calming activity, and return to bed only when sleepy.
Maintain a quiet, dark, and cool bedroom environment (the article cites approximately 65–70 degrees Fahrenheit). Blackout blinds or an eye mask can reduce light exposure.
Use a pre-bed routine of relaxing, low-light activities for 30–60 minutes before sleep, such as light reading, listening to relaxing music, a warm bath, meditation, or deep breathing. Avoid stimulating activities like screen use near bedtime.
Avoid electronic screens at least 60 minutes before bed, do not consume caffeine after about 3 pm, and avoid heavy meals within 2 hours of bedtime.
Aim for at least 30 minutes per day of heart rate–raising exercise to help reduce wake-promoting cortisol and support sleep quality.
These recommendations were attributed to clinicians quoted in the article: Scott Nass, MD, and Chelsie Rohrscheib, PhD. The article also notes that the observational findings do not prove causation and that some associations may be bidirectional or driven by underlying disease processes.