Less than 6 hours or more than 8? Your sleep duration could be ageing your body faster

Getting too little—or too much—sleep may speed up the ageing of organs throughout the body, including the brain, heart, lungs, and liver, and immune system, according to a US study published in the journal Nature.

To understand how sleep duration affects ageing across different parts of the body, researchers analysed health data from nearly 5,00,000 adults aged 37 to 84 years in the UK Biobank. They used artificial intelligence to develop 'ageing clocks' that estimate the biological age of 17 organ systems using medical images, blood proteins, and other biological markers. Unlike traditional ageing tests that provide an overall measure of ageing, these organ-specific clocks show that different organs can age at different rates.

The findings revealed a U-shaped pattern: both sleeping too little (fewer than six hours a night) and sleeping too much (more than eight hours a night) were linked to faster biological ageing. The slowest rate of biological ageing was seen in adults who regularly slept between 6.4 and 7.8 hours each night.

People who slept less than six hours were also more likely to have depression, anxiety, obesity, type 2 diabetes, high blood pressure, heart disease, and irregular heart rhythms. Both short and long sleep were linked to lung diseases, including asthma and chronic obstructive pulmonary disease (COPD), as well as digestive problems such as gastritis and acid reflux.

The researchers also found that short sleepers had a 50 per cent higher risk of dying from any cause during the study period, while long sleepers had a 40 per cent higher risk, compared with people who slept 6.4 to 7.8 hours a night.

The study highlights “the potential of sleep optimisation to promote healthy ageing, lower disease risk and extend longevity”.