Scientists discover new “sweet spot” for sleep length

Goldilocks breaking into that bear family’s house may have been unethical, but it apparently helped her uncover a new breakthrough about sleep and health.

A new Columbia University study suggests there’s a sleep “sweet spot” where the body appears to age the slowest: between 6.4 and 7.8 hours per night.

• The research team found that both too little and too much sleep were linked to accelerated aging across nearly every major organ system, including the brain, heart, and immune system.
• They analyzed self-reported sleep data from ~500,000 people, then compared it against 23 separate “biological aging clocks” that estimate how old organs appear compared to a person’s actual age.

The result? A classic U-shaped curve

People closest to the sleep sweet spot of between 6.4-7.8 hours showed the healthiest aging markers, while too little or too much sleep was linked to faster biological aging, higher disease risk, and increased mortality.

The results showed that significantly shorter sleep led to a ~50% higher relative risk for all-cause mortality, while longer sleep carried a ~40% higher risk.

An important caveat: Researchers can’t prove sleep itself caused the aging differences, only that the two are linked. Experts also stress that sleep isn’t one-size-fits-all—a healthy 23-year-old, a pregnant woman, and a 70-year-old with heart disease likely all need very different amounts of daily rest.