Sleep’s Sweet Spot for Healthy Aging

Using UK Biobank data, researchers compared nightly sleep with 23 measures of biological aging based on brain scans, blood proteins and metabolic indicators. These measures estimate how old cells and organs appear biologically. The results formed a U-shaped pattern: sleeping under 6 hours or above 8 hours was associated with wider differences between biological and chronological age than sleeping between those extremes.

The smallest aging gaps across significant measures occurred from 6.4 to 7.8 hours, although the range varied among organ systems. The findings connected sleep with aging throughout the body, including organ condition, metabolism and immune activity. They also support the importance of sleep quality and regularity, rather than focusing only on accumulating more hours.

Men and women had somewhat different optimal ranges across nine significant aging clocks. Women showed higher aging measures involving brain proteins, while men had higher measures based on brain MRI. Short sleep was associated with conditions spanning heart, metabolic, muscle and bone, and mental health systems. Longer sleep had narrower links to brain-related conditions, including depression, schizophrenia and bipolar disorder. Researchers suggested extended sleep may reflect existing health problems instead of causing harm itself. The relationship between long sleep and depression later in life was largely explained by faster aging in brain and fat tissue.