A study published on September 17, 2026, in the open-access journal PLOS Medicine by Shengzhi Sun from the Capital Medical University in China and colleagues highlights the importance of sleep cycles in health. The research analyzed data from 95,559 participants from the UK Biobank, who wore accelerometers on their wrists for seven consecutive days and nights. An algorithm was used to calculate sleep stages (REM, deep sleep and light sleep), total sleep duration, periods of wakefulness after falling asleep, and sleep irregularity from night to night. The study found that longer paradoxical sleep—also known as REM (rapid eye movement) sleep—was associated with a lower risk of 83 diseases, including heart failure and Parkinson's disease. Longer deep sleep was also linked to a lower risk of seven conditions, including type 2 diabetes and major depressive disorder. Greater sleep irregularity and more frequent awakenings after falling asleep were each associated with an increased risk of several conditions, including anxiety and substance use disorders. The researchers noted that the lowest risk was observed during a period of 6 to 8 hours of sleep. However, those who slept less than five hours presented the greatest clinical vulnerability, with an increased risk of 37 conditions. According to the Santé publique France barometer from 2024, the average sleep time is 7 hours and 32 minutes among adults aged 18 to 79 years. In the age group of 50 to 59 years, the average sleep time is shorter, with an average duration of 7 hours and 16 minutes. For those aged 18 to 29 years and 70 to 79 years, sleep durations are longer. The study authors explain that these results confirm the importance of a sleep duration of 6 to 8 hours for the health of middle-aged adults and older people, probably due to a better distribution of sleep stages. They suggest that maintaining regular sleep patterns and sufficient sleep duration could help reduce the risk of various health conditions. The findings add to the growing body of evidence linking sleep quality and quantity to overall health outcomes.