Ever wonder why you're constantly suffering from the sniffles while everyone else you know is feeling fine? It might have to do with how long you're sleeping. According to an August 2015 study published in the journal Sleep, getting too few Zzzs is the No. 1 risk factor when it comes to catching a cold.
Researchers from the University of California-San Francisco (UCSF), Carnegie Mellon, and the University of Pittsburgh studied 164 healthy men and women, ages 18 to 55. Participants filled out sleep diaries and wore sleep monitors (a more clinical version of a Jawbone Up or a Fitbit) on their wrists for a week. The scientists then quarantined them in a hotel, gave them nasal drops containing rhinovirus and monitored them over five days to see if they caught the virus and showed cold symptoms, such as congestion or extra mucus production.
The results showed a clear connection between sleep and the common cold: People who slept less than six hours a night were four times more likely to catch the virus and display symptoms than people who slept seven hours or more. People who slept from six to seven hours a night didn't see an increase or decrease in risk. Sleep was the top factor that predicted whether or not participants would get a cold, beating out factors like age, stress levels, time of year, physical activity, and even smoking.
Why the connection? "Sleep is really important for regulating the immune system," says lead author Aric Prather, PhD, assistant professor of psychiatry at UCSF. "The number of immune cells, [which are] circulating in our blood and sitting in our lymph nodes to fight off viruses, all kind of move along as we sleep throughout the night. When we don't sleep enough, it disrupts this system."
Right now, more than a third of the population isn't getting enough sleep and thus is at risk of getting sick, experts say. Both the American Academy of Sleep Medicine and the Sleep Research Society recommend getting at least seven hours of sleep each night to avoid health risk.
Sleep is just as important as diet and exercise when it comes to your overall health. "You have to eat, you have to exercise, you have to breathe, [and] you have to sleep. I think that gets lost," says Lisa Meltzer, PhD, sleep education fellow for the National Sleep Foundation and associate professor at National Jewish Health in Denver. "Having healthy sleep habits is one of those pillars that is essential." Dr. Meltzer recommends keeping a consistent sleep schedule and nixing all electronics from the bedroom to improve your sleep quality and protect your immune system.
Dr. Prather says the next research steps will be to determine which types of sleep — deep sleep, light sleep and uninterrupted sleep, to name a few — are the strongest protection against the common cold. But for now, consider this a reason to skip the Netflix binge and hit the hay early tonight.