Sleeping too little or badly weakens you in any number of ways. Now we have an experiment showing that unless you have high immunity to colds, your chances of catching a cold are four times higher if you sleep fewer than six hours a night.
Considering that the 2014-2015 cold season was rougher than usual, you might want to recommit to the goal of getting to bed earlier, or helping your kids to wind down before bedtime.
In the two-part study, scientists gathered nightly data on 164 healthy people for one week. The participants recorded when they went to bed and when they awoke, and also wore devices on their wrists to monitor movement during the time they slept. If the wrist band recorded movement, the researchers subtracted the time moving from total hours asleep.
Next, they tested the participants to see if they were especially immune to colds, and eliminated those who had high levels of antibodies.
The remaining group of gallant participants agreed to receive nose drops and live quarantined on a hotel room floor for five days. Forty of them got nose drops that were harmless; the other 124 received drops containing the cold virus.
Let’s hope some of them fell in love, or at least played lots of poker and caught up on their email and reading. Their main job was to supply scientists daily with their used tissues. To test for congestion, the scientists also dripped a harmless dye into their noses and measured how long it took to reach the back of their throats.
A tissue that contained too much snot counted as a sign of illness. Another sign was if it took longer than 35 minutes for the dye to reach the throat. A participant was considered to have a cold if he had at least one of those two signs and a sample from his nasal passage showed signs of the virus or bloodwork revealed higher levels of rhinovirus antibody.
Forty-eight got colds. It turned out that 45.2 percent of those who had who slept fewer than five hours a night during the test week caught the cold, compared to 17.2 percent of those who slept seven hours or more. Thirty percent of people who had slept five to six hours got sick.
“Sleep often takes a back seat to other health behaviors like nutrition and exercise,” says Aric Prather, lead author of the study and a sleep researcher at the University of California in San Francisco, adding that the experiment “provides some really clear evidence for those people who get less than 5 or 6 hours of sleep — there really is a clear biological cost.”
Some other cold-fighting tips: take at least 75 mg of zinc within 24 hours of the first symptoms. To prevent catching one, disinfect your smartphone, office surfaces, and gym equipment, and rinse your nose with saline solutions.
November 04, 2015
Christopher Nystuen, MD, MBA