Poor sleep correlates with aging, but may not cause it

The assumption that chronic poor sleep drives aging has fueled an entire industry of sleep optimization products. But the researchers, working with five independent datasets, found that the picture is considerably more nuanced.

The study confirmed a robust correlation between poor sleep and a higher biological age, measured using multiple aging clocks (biomarkers that estimate how quickly a person’s body is aging). This correlation held across young adults, middle-aged adults, and older people. It also persisted after accounting for chronic disease burden.

Twin data complicates the story

When the researchers looked specifically at twin pairs, however, the association largely disappeared. Twins share genetic backgrounds and early environmental exposures. The fact that the correlation fades when controlling for these shared factors suggests that genes or early-life circumstances may independently drive both poor sleep and faster aging, without one directly causing the other.

The team also tested causation using Mendelian randomization, a technique that uses genetic variants as a natural experiment to probe causal relationships. The results were mixed. Some analyses pointed toward a causal effect of poor sleep on accelerated aging; others did not.

Downstream effect of aging?

The authors suggest that poor sleep in older adults may largely be a consequence of aging rather than a driver of it. Aging brains and organs function differently, and that can disrupt sleep. The association observed in population data may therefore reflect the reverse direction: aging makes sleep worse, not the other way around.

From a longevity perspective, this matters. Sleep is widely promoted as a modifiable lever for extending healthspan. This study does not overturn the importance of sleep for health, but it does suggest that the specific claim that improving sleep slows biological aging is not consistently supported by the current evidence.

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