Researchers found people who got less sleep during the week, but slept in on weekends had the same mortality rate as people who got seven hours of sleep each night.
Over a decade was spent following nearly 44,000 people in Sweden to come up with the findings.
There's no obvious answer on why this makes a difference. One professor from the Stress Research Institute at Stockholm University thinks people are possibly catching up on lost sleep.
The study was published in the Journal of Sleep Research.