Study links 6.4 to 7.8 hours of sleep with slower biological ageing
Columbia University researchers who analysed data from nearly half a million people found the best biological ageing indicators among those sleeping 6.4–7.8 hours a night. The study does not prove that sleep duration itself causes ageing.
Researchers at Columbia University have examined data from nearly half a million people to find which sleep duration is linked to the most favourable biological ageing indicators, according to the news site Unian.net. The optimal range turned out to be 6.4 to 7.8 hours a day, while both too little and too much sleep were associated with faster ageing of the body.
What was studied
The scientists assessed 23 biological ageing markers, which help gauge the condition of various organs and tissues. In total, 17 body systems and structures were covered, including the brain, heart, lungs and immune system.
The best results were seen in people who slept roughly 6.4–7.8 hours. Those who slept less than six hours or more than eight showed signs of accelerated biological ageing more often. The relationship was U-shaped: the least favourable values appeared at both extremes of sleep duration, and the best in the middle of the range.
Possible explanations
Chronic sleep deprivation can upset hormonal balance, intensify the body's stress response and interfere with recovery processes. It may also affect blood sugar levels and blood pressure regulation. Excessively long sleep is a more complex matter: it is not necessarily harmful in itself, but may be tied to chronic illness, mental health disorders or poor sleep quality. The researchers therefore stress that the study does not prove sleep duration directly causes faster or slower ageing; it may rather be an important indicator of overall health.
Links to disease
People who slept less than six hours a day more often had depression, anxiety disorders and obesity. Associations were also found with type 2 diabetes, high blood pressure, coronary heart disease and heart rhythm disorders. Both insufficient and excessive sleep were linked to a higher risk of respiratory and digestive diseases, including asthma, gastritis and gastroesophageal reflux disease.
Takeaways
Adults are generally advised to sleep at least seven hours, though individual needs can vary. Sleep quality and a regular schedule also matter. If a person regularly sleeps significantly more or less than usual and still feels tired, it may point to health problems worth discussing with a doctor.
