Sleeping is not an interval between one day and another, but an active process of biological repair that involves the brain and organs. New research published in Naturebased on the work of the MULTI Consortium and data from the UK Biobank, analyzed half a million people to understand how sleep duration influences biological aging.
Scientists have used advanced tools such as magnetic resonance imaging, protein and metabolic profiles to build true “biological age clocks”, capable of measuring how rapidly an organ ages compared to its chronological age. The result is a complex snapshot of the human body as an interconnected system.
The key finding: a U-curve between sleep and aging
The analysis showed a recurring U-shaped pattern: both insufficient sleep (less than 6 hours) and excessive sleep (over 8 hours) are associated with faster aging. The sweet spot is between approximately 6.4 and 7.8 hours of daily rest.
In this window, biological clocks indicate a “younger” organism, with benefits observed in different systems: brain, heart, lungs, metabolism and immune system. The data does not indicate a rigid cause-effect relationship, but a strong association between sleep duration and general physiological balance.
The “biological clocks” that measure the age of organs
The research team developed 23 clock models of aging based on medical imaging, proteomics and metabolomics. Each organ, from the liver to the brain, shows different rates of deterioration, and these tools allow us to quantify them with increasing precision.
These clocks reveal that the body does not age uniformly: some tissues can “age earlier”, others more slowly. Sleep appears as a transversal factor that influences this internal synchronization, acting on multiple biological levels simultaneously.
When sleep drifts away from equilibrium: systemic risks
According to the data analyzed, both short and prolonged sleep are associated with an increased risk of pathologies such as depression, anxiety, type 2 diabetes, hypertension, cardiovascular diseases and respiratory disorders. The digestive system is also involved.
At both extremes, the risk of mortality increases significantly compared to the average. Researchers hypothesize that excessive sleep may also be a sign of underlying conditions, while insufficient sleep acts directly on the biological mechanisms of stress and inflammation.
A dynamic balance between brain, body and biological time
The study suggests that sleep is not just a brain function, but a coordinated biological network that regulates the entire organism. The differences between organs and individuals mean that there is no absolute universal rule, but an optimal window in which the system works best. Factors such as gender and metabolism also slightly influence the ideal length of sleep, but the general principle remains the same: the body seems to “rejuvenate” when sleep stabilizes in a specific interval.
Towards a new idea of health linked to sleep
The research opens up a broader vision of health, in which regulated sleep becomes a central indicator of longevity. It’s not just about quantity, but about balance. The final message from scientists is clear: sleep is not a waste of time, but one of the main tools with which the body controls its aging.
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