Scientists Found a Surprising Connection Between Dreaming and 83 Diseases

Key Points:

• A large UK study involving nearly 100,000 adults found that spending more time in REM sleep is associated with a lower risk of developing 83 different health conditions, including heart failure, dementia, and Parkinson’s disease.
• Researchers used wrist-worn accelerometers and a machine-learning algorithm (SleepNet) to estimate sleep stages, linking sleep patterns with hospital records over a median follow-up of 8.9 years.
• The study highlighted that REM sleep proportion matters independently of total sleep duration, with greater REM sleep linked to significantly reduced risks for many diseases; deep sleep also showed protective effects but across fewer conditions.
• While sleep duration was related to 86 disease outcomes, the lowest risk was generally associated with sleeping six to eight hours, and very short sleep (<5 hours) showed the most adverse health associations.
• Limitations include the indirect measurement of sleep stages via wrist movement, potential confounding factors, a predominantly White participant group, and reliance on hospital records, meaning causality cannot be established and findings may not generalize broadly.