Not just lack of sleep: scientists find unexpected link to aging

A large-scale study involving 500,000 people, published in Nature, has revealed a U-shaped relationship between sleep duration and biological aging of organs. The optimal range is 6.4–7.8 hours; deviations in either direction accelerate aging of the heart, lungs, liver, and brain.

Researchers from the MULTI consortium analyzed data from 500,000 people aged 37 to 84, using 23 biological 'aging clocks' based on MRI, blood tests, and metabolic tests. The results, published in the journal Nature, showed that the relationship between sleep duration and biological age of organs is U-shaped: minimal aging is observed with 6.4–7.8 hours of sleep per day. Deviation in either direction accelerates aging of the heart, lungs, liver, brain, immune system, skin, endocrine system, adipose tissue, and pancreas. The authors identified 153 significant links between disrupted sleep duration and future diseases. Short sleep (less than 6 hours) more strongly impacts mental health, heart, lungs, metabolism, and digestion, while long sleep (more than 8 hours) is associated with neuropsychiatric disorders through accelerated aging of the brain and adipose tissue. The researchers acknowledge limitations: sleep duration was self-reported by participants, and sleep quality and bedtime were not considered. In older adults, short sleep may be a consequence of aging rather than a cause.