The type of sleep a person gets, rather than just the duration, influences the risk of developing dozens of diseases later in life, a large study of nearly 100,000 people reveals.
Previous research establishes that getting six to eight hours of sleep daily reduces the risk of several health conditions, including diabetes and heart disease.
But how specific sleep stages and real-world sleep patterns relate to health outcomes remains largely unclear. This is mainly because most studies use self-reported sleep measures, which often show poor correlation with objective assessments, making it difficult to capture real-world sleep patterns.
To overcome this, researchers at Peking University in China analysed the health data of 95,559 people from the UK Biobank, a research resource which stores biological, genetic, and lifestyle information of 500,000 volunteer participants in the UK. The people included in the study wore wrist accelerometers for seven consecutive days and nights.
Researchers analysed the duration of each sleep stage – REM, deep sleep, light sleep – as well as the total sleep duration, wakefulness after sleep onset, and night-to-night sleep irregularity.
They tracked each participant for an average of nine years and checked their health records for links with more than 1,000 disease outcomes.
Researchers found that more REM sleep was associated with a lower risk of 83 diseases, including heart failure, dementia, and Parkinson’s.
Greater deep sleep was linked with a lower risk of seven conditions, including type 2 diabetes and clinical depression.
Higher sleep irregularity and wakefulness after sleep onset, on the other hand, were linked to a higher risk of conditions like anxiety and substance-use disorders.
Researchers noted that study participants who regularly slept for six to eight hours carried the lowest risk of several diseases. Participants who slept less than five hours faced the most elevated clinical vulnerability, with a higher association for 37 health conditions, but those sleeping more than eight hours were at risk as well.
“The minimum-risk duration for the majority of these conditions was precisely concentrated within the 6-8 hour window,” researchers wrote.
However, they cautioned that the findings were only observational and could not establish that sleep patterns directly caused disease risk.
“The findings provide additional evidence supporting the role of a 6-8 hour sleep duration as a health safeguard for middle-aged and older adults, likely attributable to more favourable distributions of the sleep stages,” the study said. “Maintaining a sleep duration of 6-8 hours can effectively reduce the risk of multiple diseases, providing new insights for health promotion and preventive practice.
