MONDAY, Jan. 12, 2009 (Health.com) — Are you getting enough sleep? If not, it could be hurting your health. A new study suggests that people who lose just a bit of sleep, or those who have poor quality sleep, are more likely to get sick after being exposed to a cold virus than those who get more shut-eye.
“People who slept less than seven hours were about three times more likely to get a cold than people who slept eight hours or more a night,” Sheldon Cohen, PhD, of Carnegie Mellon University, in Pittsburgh, said in a podcast. The study was published Monday in Archives of Internal Medicine.
Cohen and his colleagues interviewed 153 men and women ages 21 to 55 every day for two weeks; they asked how long they slept, how much they tossed and turned before dropping off, and whether they felt rested in the morning, in addition to other factors.
After that, the study subjects were quarantined for six days and given cold-virus-containing nose drops at a dose about 125 times the amount that it takes to infect cells in a laboratory.
The researchers measured everything from symptoms to the weight of nasal secretions (discarded tissues were weighed in a plastic bag, and the weight of the tissue and bag subtracted) to determine who became infected.
They found that 88% of people became infected with the virus (as measured by cold virus in their nose or antibodies in their blood), but not all of those people actually got sick. About 43% of the volunteers had signs of infection plus cold symptoms, such as a stuffy nose, cough, and sore throat.
“People whose sleep was disturbed were much more likely to develop colds than people who went to sleep, slept all night, and got up in the mornings,” said Cohen.
Study subjects who had less than seven hours of sleep were at greater risk than those who got eight hours of sleep a night. And those with lower sleep efficiency—the amount of time they spent in bed asleep—were at higher risk too. People with a sleep efficiency of less than 92% had a 5.5-times greater risk of developing a cold than those with a 98% or more sleep efficiency.
“If an eight-hour sleeper lost as little as 10 minutes of sleep a night, they could be three and a half times more likely to get colds; if they lost as much as 40 minutes of sleep on an average night, they were over five times as likely to get a cold,” said Cohen.
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