If you don't catch 40 winks, you may catch a cold, according to a new Carnegie Mellon University study.
People who sleep fewer than seven hours a night are nearly three times more likely to get a cold than those who average eight or more hours of sleep, the study found.
For people who wake up periodically or have trouble falling asleep, the news is even worse.
Study subjects who missed out on shuteye for as little as 8 percent of the time they were laying in bed were five-and-a-half times more likely to get the sniffles than those who slept throughout the night.
"Although sleep's relationship with the immune system is well-documented, this is the first evidence that even relatively minor sleep disturbances can influence the body's reaction to cold viruses," said Sheldon Cohen, the Robert E. Doherty Professor of Psychology at Carnegie Mellon and lead author of the study. "It provides yet another reason why people should make time in their schedules to get a complete night of rest."
In the study, published in the Jan. 12 issue of the Archives of Internal Medicine, 153 healthy volunteers were introduced to a cold virus. They were then sequestered in a hotel for five days and monitored for symptoms, such as sneezing, nasal congestion and sore throats. Of the study subjects, 54 developed a cold.
Additionally, for two weeks prior to their participation in the study, the 78 men and 75 women were interviewed daily regarding the quality of their sleep the previous night.
In the measurement category of duration — or length of sleep — people who reported less than seven hours of sleep were 2.94 times more likely to become symptomatic than were subjects who reported eight or more each night.
With sleep efficiency — or the percentage of time one actually sleeps between lying down to sleep and waking up the next morning — those who scored lower than 92 percent sleep efficiency were five-and-a-half times more likely to develop colds than those with efficiency scores of 98 percent or better.
Interestingly, how rested subjects felt didn't correlate with the eventual development of cold symptoms.
The study is unique in its examination of the daily sleep habits of otherwise healthy people. The statistical analysis controlled for other potential confounding factors — such as smoking, stress and depression.
"Experiments that explore the relationship between sleep and immune function often involve sleep deprivation or study subjects with sleep disorders, which are often rooted in psychiatric conditions that influence other aspects of health," Cohen explained. "This research points to the role played by ordinary, real-life sleep habits in healthy persons."
Other article co-authors were William J. Doyle and Cuneyt M. Alper from the University of Pittsburgh, Denise Janicki Deverts from Carnegie Mellon and Ronald B. Turner from the University of Virginia.
The research was funded with grants from the National Heart, Lung and Blood Institute, the National Institute of Allergy and Infectious Diseases, and the John D. and Catherine T. MacArthur Foundation Network on Socioeconomic Status and Health.