Waking up through the night ‘raises risk of 83 diseases from heart failure to dementia’

WAKING up during the night could raise the risk of up to 83 diseases, scientists claim – from heart failure to dementia. A lot of focus is given to how many hours of kip we get each night – the NHS recommends seven to nine hours for adults. But the quality of your sleep is just as important as the quantity of hours you get each night, new research suggests. Greater REM sleep was associated with a lower risk of 83 health issues Greater amounts of rapid eye movement (REM) – when most dreams happen – and deep sleep are associated with lower risks of dozens of diseases, said scientists. Sign up for the Health newsletter Thank you! But less than five hours of total sleep per night is linked with higher risk of illness, according to the findings published in the journal PLOS Medicine. The evidence also suggests that six to eight hours of sleep per night really is a “health safeguard” for middle-aged and older adults. The study involving more than 95,000 British participants used wrist-worn accelerometer data to map associations between real-world sleep patterns and the incidence of more than 1,000 health conditions. The findings showed greater REM sleep was associated with a lower risk of 83 health issues – including heart failure, dementia and Parkinson’s disease. More hours of deep sleep were linked to lower risk of seven conditions, including type 2 diabetes and major depressive disorder. Meanwhile, greater sleep irregularity and wakefulness during the night were each linked to higher risk of several conditions, including anxiety and substance use disorders. Most read in Health The research was led by Professor Shengzhi Sun of Capital Medical University in Beijing, China. The most recent 2026 China Sleep Health White Paper found that while the average surveyed Chinese person sleeps 6.97 hours per night, 23 per cent sleep less than six hours per night. The same report noted that only 26 per cent of respondents reported a consistent sleep schedule, and that disturbances to shuteye have increased over time. Understanding how sleep patterns are linked to disease risk is therefore of great relevance, Prof Sun said. He said: “There remains limited understanding of how sleep stages and other real-world sleep patterns relate to health outcomes. “In part, that is because self-reported sleep measures often show poor correlation with objective assessments, making it difficult to capture real-world sleep patterns.” For the new study, researchers analysed data from 95,559 UK Biobank participants who wore wrist accelerometers for seven consecutive days and nights. The Chinese team used a deep-learning algorithm to calculate stages of REM, deep, and light sleep, total sleep duration, wakefulness after sleep onset, and night-to-night sleep irregularity. Participants were followed for an average of 8.9 years, and health records were available to test for associations with more than 1,000 different illnesses. The findings also showed that there was no straightforward link between total sleep duration and the risk of many health issues. The lowest risk concentrated in a six- to eight-hour sleep window. People sleeping less than five hours had the highest health risks, as they were more likely to develop 37 conditions. But since the study was observational, Prof Sun noted that it can’t establish that sleep patterns directly cause disease risk. He said: “The findings provide additional evidence supporting the role of a six to eight hours’ sleep duration as a health safeguard for middle-aged and older adults, likely attributable to more favourable distributions of sleep stages. “Maintaining a sleep duration of six to eight hours can effectively reduce the risk of multiple diseases, providing new insights for health promotion and preventive practice.” Prof Sun added: “Sleep duration exhibited significant non-linear associations with 86 disease phenotypes, with the minimum-risk duration for the majority of these conditions, 69 phenotypes, precisely concentrated within a six- to eight-hour window.” Comment now