The Bad Habit That Makes You 4 Times More Likely to Catch a Cold


About 35 percent of U.S. adults report sleeping less than seven hours per night. (Photo: Tom Merto/Getty Images)

To avoid catching a cold, catch some ZZs. People who sleep fewer than six hours per night have more than four times the odds of coming down with a cold, compared with people who sleep more than seven hours, finds a new experimental study.

“The results surprised me in how striking they were,” study author Eric A. Prather, PhD, of the University of California, San Francisco, tells Yahoo Health.

Numerous studies have observed that short sleepers are more susceptible to colds. Laboratory research also shows that sleep deprivation alters the immune system. “However, much of this work is based on either a person’s self report of their sleep, which can be biased, or laboratory studies where sleep is restricted, which is a sort of extreme sleep loss not typical for the average person,” Prather explains.

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So Prather and colleagues set up an elaborate experiment: They set up 164 adults in a hotel for about a week and tracked their sleep objectively using a wrist monitor. After the first week, the researchers gave the healthy study participants nasal drops containing the virus that causes most cases of the common cold (rhinovirus) — simulating what would happen if someone were to, say, inhale particles from a sick person’s cough or sneeze. The subjects were then quarantined for another five days, putting their tissues in baggies so that researchers could weigh how much snot they were producing, and subjecting to a nasal clearance test to check for stuffy nose.

The difference between short sleepers and sound snoozers was striking: People who slept fewer than six hours a night the week before viral exposure were substantially more likely to catch a cold than people who slept more than seven hours a night. And even when researchers statistically accounted for factors like stress, smoking, and body weight, sleep continued to be a strong predictor of catching a cold.

Related: Can You Catch Up on Sleep?

“Laboratory studies show that when people don’t get as much sleep as they would usually get, the immune system is disrupted in ways that are likely important to protection against viruses,” Prather explains. Sleep deprivation changes the function of virus-fighting T and B cells in ways that make the body less prepared to ward off colds, he adds.

This is the first study to show that short sleep duration, measured objectively, is associated with increased susceptibility to a cold following viral challenge, Prather says. “This is significant because up until now there was not a lot of clear experimental evidence that short sleep conferred risk for a hard clinical outcome,” he explains. “While we can’t say for certain what is going wrong with the immune system among short sleepers — it’s probably more than just one thing — we can say that when it comes to a coordinated process like protecting us from the cold, short sleepers are not doing as well.”

Consider sleep a vital health habit, up there with being physically active and eating well, Prather advises: “It is my hope that this study and studies like this will help crystalize the notion that sleep is critical to health and well-being, and that consistent lack of sleep can have real health consequences.”

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