A new large-scale study has found that both too little and too much sleep may be associated with faster biological ageing and a higher risk of several diseases affecting major organs.
Researchers analysing data from nearly half a million participants in the UK Biobank identified a consistent pattern showing that sleep duration plays a significant role in how quickly the body ages at a biological level. The findings suggest that people who regularly sleep fewer than six hours or more than eight hours a night tend to show signs of accelerated ageing compared with those who fall within the middle range.
The study used so-called biological ageing clocks, which estimate how quickly a person is ageing compared with their actual chronological age. These tools rely on machine learning models that interpret biological indicators such as brain scans, blood proteins and chemical markers.
Across multiple organs, including the brain, lungs, liver, skin, immune system and metabolic pathways, researchers observed a U-shaped relationship between sleep duration and ageing. Individuals who maintained moderate sleep levels generally showed healthier biological profiles, while those at either extreme displayed more signs of accelerated decline.
Short sleep was strongly associated with brain-related conditions such as depression and anxiety, reinforcing earlier findings on the connection between sleep and mental health. It was also linked to a wider range of diseases, including heart disease, type 2 diabetes, obesity, asthma and digestive disorders.
Long sleep duration was also associated with poorer health outcomes, although researchers caution that excessive sleep may in some cases reflect underlying illness rather than being a direct cause of health problems.
Junhao Wen, lead author of the study and assistant professor of radiology at Columbia University Vagelos College of Physicians and Surgeons, said the results highlight sleep as a core element of overall physiological health.
“The broad brain-body pattern is important because it tells us that sleep duration is a deeply embedded part of our entire physiology, with far-reaching implications across the body,” Wen said.
He added that the findings support the idea that sleep is not only linked to brain health but also plays a role in maintaining balance across multiple organ systems, including metabolic regulation and immune function.
While the results strengthen the association between sleep and ageing, researchers emphasise that the study does not prove causation. Much of the sleep data relied on self-reported information, which may not always accurately reflect actual sleep behaviour.
Experts involved in the study say further research is needed to determine whether abnormal sleep patterns directly accelerate ageing or whether existing health conditions influence sleep duration.
They also recommend future studies using more precise sleep tracking methods and broader population samples to better understand how sleep habits affect long-term health.
