A new study proves that the number on defense against colds is getting enough sleep. Although doctors have long known that lack of sleep can make you more prone to illness, a pivotal new study proves just how crucial sufficient shuteye really is. After being exposed to the common cold virus, healthy adults who regularly got less than six hours per night were four times more likely to actually get sick than those who slept seven hours.
While most sleep studies have participants self-report their sleep patterns, which is notoriously inaccurate, this trial was far more advanced. For one week, 164 otherwise healthy men and women, average age 30, wore a FitBit-like wrist sensor at home while they snoozed. This measured their sleep quality and duration and provided the researchers with a picture of what a normal week of sleep looked like for these folks. Next, they were quarantined in a hotel and given nasal drops laced with rhinovirus. Then every day for the following week, the researchers collected mucus samples to determine, via the number of antibodies present, whether the infection had taken hold. To gauge cold symptoms, they also measured the volunteers' levels of congestion and collected and evaluated every tissue they blew their noses on throughout the week.
Of the participants who'd slept at least six hours per night the week prior to being exposed to the virus, only 18 percent actually got sick. By contrast, 39 percent of those who logged less than six hours wound up with a cold. Looking at the data another way, the researchers determined that if you sleep seven or more hours per night and you become exposed to the virus, your odds of catching the cold are only 17 percent. The risk jumps up to 23 percent if you get six to seven hours of sleep, 30 percent if you log five to six hours, and a whopping 45 percent if you sleep for less than five.
"What can I say? Sleep is a hugely important health behavior and one that's oftentimes neglected," says study author Aric Prather, a psychiatry professor at the University of California, San Francisco. "Sleep bolsters the immune system in several ways. When you're deprived, T cells — the body's army against viruses — don't proliferate. Inflammation also increases throughout the body." Prather says these results also prove that insufficient sleep influences cold susceptibility more so than body weight, age, smoking, and even excess stress.
Lack of sleep is a chronic problem for too many of us. According to a recent National Sleep Foundation survey, American adults average just 6 hours and 31 minutes of shuteye on workdays, while the amount needed to function optimally is 7 hours, 13 minutes. Sixty-nine percent of us get less sleep than we need during the workweek; 42 percent don't even sleep enough on the weekends.
"Sleep too often takes back seat to nutrition, exercise, and other healthy behaviors we spend time investing in," Prather says. "After we fill up our whole day, we allocate whatever time is left over for sleep — and studies like this show that's a big detriment to our health."