A growing body of research has shown that sleep matters for health, but a new nationwide analysis suggests it matters even more than many people realize. According to researchers at Oregon Health and Science University, consistently getting too little sleep is one of the strongest predictors of shorter life expectancy in the United States, surpassed only by smoking.
The findings challenge the idea that sleep is optional or something that can be postponed and made up later. Instead, researchers say sleep should be treated as a core pillar of long term health, just like diet and exercise.
The study was led by scientists at Oregon Health and Science University, with senior author Andrew McHill, Ph.D., an associate professor in the OHSU School of Nursing, the OHSU School of Medicine, and the Oregon Institute of Occupational Health Sciences. Much of the research work was conducted by graduate students in the Sleep, Chronobiology and Health Laboratory at OHSU.
The study was published in the journal SLEEP Advances and was supported by funding from the National Heart, Lung, and Blood Institute of the National Institutes of Health, along with institutional support from OHSU and the state of Oregon.
How the Study Was Conducted
Researchers analyzed a massive nationwide dataset covering all 3,143 U.S. counties over a six year period from 2019 through 2025. They compared county level life expectancy data with health and behavior survey data collected by the Centers for Disease Control and Prevention.
The analysis examined how often people reported getting insufficient sleep and compared that information with average life expectancy in each county. The researchers also accounted for many other factors commonly linked to health outcomes, including smoking, obesity, physical inactivity, diet, and other behavioral risks.
For the purpose of the study, the CDC defined sufficient sleep as at least seven hours per night, a standard recommended by both the American Academy of Sleep Medicine and the Sleep Research Society.
What the Research Found
The results were striking and consistent. Counties where more people reported sleeping fewer than seven hours per night had shorter life expectancies, year after year and across nearly every U.S. state.
As a behavioral predictor of life expectancy, insufficient sleep ranked higher than diet, exercise, loneliness, unemployment, or education level. Only smoking showed a stronger association with shorter lifespan.
“I didn’t expect it to be so strongly correlated to life expectancy,” McHill said. “We’ve always thought sleep is important, but this research really drives that point home.”
In some cases, neighboring counties showed sharp contrasts. A county where about 40 percent of residents slept fewer than seven hours could sit next to one where only 25 percent did, with a life expectancy gap of several years between them.
Although previous studies have linked poor sleep to higher mortality risk, this research is the first to show clear year to year correlations between sleep duration and life expectancy across every U.S. state.
Sleep plays a critical role in cardiovascular health, immune system function, metabolic regulation, and brain health. Chronic sleep deprivation has been associated with increased inflammation, ongoing stress responses, and disruptions that raise the risk of heart disease, diabetes, stroke, depression, and neurodegenerative conditions.
McHill noted that sleep influences nearly every major system in the body, which helps explain why its relationship with lifespan appears so strong.
How Much Sleep Is Considered Enough
For people who regularly cut sleep short, the findings carry a clear warning. Even if someone eats well and exercises, consistently sleeping fewer than seven hours a night may still place them at higher risk for a shorter life.
Many people treat sleep as flexible, assuming they can catch up on weekends or sacrifice rest temporarily during busy periods. The research suggests that this mindset may come at a long term cost.
“We think of sleep as something we can set aside and maybe put off until later,” McHill said. “This research shows that we need to prioritize sleep at least as much as we do what we eat or how we exercise.”
In this study, sufficient sleep was defined as at least seven hours per night. McHill and his colleagues emphasized that most adults should aim for seven to nine hours of sleep whenever possible, in line with national sleep guidelines.
This range is not presented as a luxury or an ideal scenario, but as a baseline requirement for maintaining health and supporting longevity.
The strength of the findings surprised even sleep experts. McHill described the association between sleep sufficiency and life expectancy as remarkable, even given his background as a sleep physiologist.
Outside experts have echoed the concern. Sleep medicine physicians note that sleep functions as a biological reset for the body, and that long term sleep deprivation can gradually increase the risk of serious chronic disease.
While the researchers caution that correlation does not automatically prove causation, the consistency of the data across geography, income levels, and time makes the findings difficult to dismiss.
As McHill put it, getting a good night’s sleep does more than improve how you feel the next day. “Getting a good night’s sleep will improve how you feel,” he said, “but also how long you live.”
