Diet and exercise can both influence how long you live, but research suggests they're not the single greatest predictor of longevity.
According to a study published in Sleep Advances, something else might have a bigger effect on your lifespan.
While poor sleep has been previously linked to a host of health issues, this investigation found that getting enough shut-eye had a stronger connection to living longer than diet and exercise – factors that are known to add years to your life.
Researchers from Oregon Health & Science University (OHSU) crunched the numbers on county-level survey data from across the US, from 2019 to 2025.
They compared measures of life expectancy with self-reported sleep duration, using less than seven hours per night as the threshold for insufficient sleep.
They then factored in other variables that can affect life expectancy, including physical inactivity, employment status, and educational level.
The association between insufficient sleep and lower life expectancy remained statistically significant after including those factors.
In the first model, only smoking had a stronger association with life expectancy. In a second model that added obesity and diabetes, obesity also ranked above insufficient sleep.
"I didn't expect [insufficient sleep] to be so strongly correlated to life expectancy," said OHSU sleep physiologist Andrew McHill.
"We've always thought sleep is important, but this research really drives that point home: People really should strive to get seven to nine hours of sleep if at all possible."
As a purely observational study, the research, published in 2025, can't prove that less sleep knocks months or years off your life.
A study like this also can't untangle the complex interactions between sleep, diet, and exercise. The results do suggest the amount of sleep you get each night is a significant indicator of long-term health.
Adequate sleep is vital to almost every aspect of our well-being: missing a single night of slumber can impact brain circuitry and the body's immune system, for example.
It's reasonable to suggest that these health issues may contribute to mortality in the long run. In particular, the researchers highlight obesity and diabetes as two conditions linked with poor sleep that could reduce life expectancy.
"It's intuitive and makes a lot of sense, but it was still striking to see it materialize so strongly in all of these models," said McHill.
"I'm a sleep physiologist who understands the health benefits of sleep, but the strength of the association between sleep sufficiency and life expectancy was remarkable to me."
The good news is that our sleep routines are, at least to some extent, modifiable within the limits of our caregiving and work commitments.
It might be worth quitting that habit of doomscrolling in bed, or squeezing in a session of yoga or tai chi now and then.
Both the American Academy of Sleep Medicine and the Sleep Research Society recommend getting at least seven hours of sleep a night, although some evidence suggests you might be able to catch up on the weekends if you need to.
"This research shows that we need to prioritize sleep at least as much as we do what we eat or how we exercise," said McHill.
"Getting a good night's sleep will improve how you feel but also how long you live."
The research has been published in Sleep Advances.
This article was fact-checked by Rebecca Dyer and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.