New research emphasizes that not all sleep stages are equally beneficial for brain health. Specifically, higher levels of rapid eye movement (REM) sleep are linked to reduced risks for 83 different diseases, which notably include dementia, Parkinson’s disease, and heart failure. Furthermore, increasing deep sleep is correlated with lower risks across seven other health conditions.
This information comes from a comprehensive study involving 95,559 adults who wore wrist accelerometers around the clock for a week. Researchers in China utilized deep-learning algorithms to examine various sleep metrics, such as REM sleep, deep sleep, light sleep, overall sleep duration, wakefulness after initially falling asleep, and sleep irregularity. They then cross-referenced this data with health records spanning nearly nine years to identify associations with over 1,000 diseases.
The analysis revealed that heightened REM sleep was associated with a notable decrease in the risk of various diseases—an 80% reduced risk for Parkinson’s, 46% for dementia, and 26% for heart failure. Additionally, more deep sleep correlated with lower risks of specific conditions, including Type 2 diabetes and major depressive disorder.
Interestingly, sleep duration also played a significant role in health outcomes. The study suggested that six to eight hours of sleep per night represented the “sweet spot” for minimizing risks associated with 69 diseases. In contrast, consistently getting less than five hours per night was linked to increased risks for 37 health issues.
Irregular sleep patterns and longer wakefulness during the night were found to be associated with heightened risks for anxiety and substance use disorders. The findings appeared in the journal PLOS Medicine on September 17.
Experts pointed out that it’s crucial to consider both the total duration of sleep and the percentage dedicated to REM sleep. Dr. Oki Ishikawa, an expert in pulmonary, critical care, and sleep medicine, stated that, generally, REM sleep should constitute about 20-25% of sleep cycles. However, he also cautioned that merely having more REM sleep doesn’t directly equate to a lower risk of diseases.
Dr. Chelsie Rohrscheib, a sleep expert at Wesper, pointed out another angle: disrupted sleep could signify an early health concern rather than just being a byproduct of disease. She noted that conditions like Parkinson’s and dementia may disrupt sleep long before they’re diagnosed, illustrating a bidirectional relationship where poor sleep might exacerbate disease progression.
The researchers acknowledged certain limitations in their study. As it was observational, the findings could only suggest correlations rather than establish direct causation between increased REM or deep sleep and disease prevention. Relying on wrist devices for only a week, they might not provide the most accurate measurement of sleep stages compared to a clinical sleep study.
Furthermore, the sample was drawn from the UK Biobank, which is less diverse and generally healthier than the broader population, putting into question how broadly the results might apply. Overall, while changes in sleep patterns can indeed offer valuable insights into health, it remains uncertain whether poor sleep is merely a symptom, a precursor, or both.
Moving forward, more research is necessary to determine the potential causal relationship between sleep stages and disease risk. Experts suggest adhering to general sleep hygiene practices, such as creating a conducive sleep environment and maintaining consistent sleep schedules.
Dr. Ishikawa further advised addressing any underlying sleep issues like sleep apnea to enhance the quantity of REM sleep. Although measuring REM sleep accurately requires specific tools, feeling refreshed upon waking is a good indicator of adequate sleep. Ideally, getting seven to nine hours of uninterrupted sleep allows for sufficient REM cycles.
