Many health studies are based on questionnaires, or experiments conducted in petri dishes. This is not one of those. In a study published in the September issue of the journal Sleep, 164 people were given trackers that monitored their sleep for a week. The human guinea pigs came back to the lab where they had a live cold virus shot up their noses. Then they were quarantined in a hotel for five days, where the researchers noted who got sick and who didn't. (Sounds like a blast.)
Even controlling for factors like body-mass index, age, stress, and pre-study antibody levels, the amount of sleep participants got was a strong predictor of infection. People who averaged six hours of sleep or fewer were four times more likely to come down with a cold than people who slept at least seven hours, Time reports. That risk went up to 4.5 times if people slept less than five hours.
NPR crunched the numbers a different way: 39 percent of people who logged six hours or less per night got sick, versus 18 percent of people who got more than that. "Striking" is how the lead author described that finding to NPR. If you tend to get colds a lot and your sleep is somewhat pathetic, maybe try to log some more shut-eye.
The study wasn't designed to determine how sleep affects immunity, but it's proof of concept that the two are connected. We imagine there will be additional studies investigating that link, and we thank those volunteers in advance.