Sleeping for less than seven hours each night significantly increases the odds of catching a cold, according to results of a recently published study.

Sheldon Cohen, of Carnegie Mellon University, Pittsburgh, and colleagues studied 153 healthy men and women with an average age of 37. Participants were first interviewed about their sleep habits, with researchers asking how many hours they slept per night, what percentage of their time in bed was spent asleep (sleep efficiency), and whether they felt rested. They were then quarantined and given nasal drops containing rhinovirus, the cause of the common cold. For the next five days participants reported any signs and symptoms of illness and had mucus samples collected from their nasal passages laboratory testing. Participants also submitted a blood sample for testing to determine whether participants' had developed antibodies to fight infection.

Results showed that participants who slept for less than 7 hours each night were nearly three times (2.94) more likely to develop a cold than those who slept for 8 hours or more each night. The results also showed that sleep efficiency was also important. Participants who spent less than 92% of their time in bed asleep were five-and-a-half times more likely to become ill than those who were asleep for at least 98% of the time they were in bed. The authors write: “A possible explanation for this finding is that sleep disturbance influences the regulation of pro-inflammatory cytokines, histamines and other symptom mediators that are released in response to infection.”

The researchers concluded that people should aim for seven to eight hours sleep each night.

Cohen S, Doyle WJ, Alper CM, Janicki-Deverts D, Turner RB. Sleep Habits and Susceptibility to the Common Cold. Arch Intern Med. 2009;169:62-67.

News release: Getting Less Sleep Associated With Lower Resistance to Colds. American Medical Association. January 12th 2009.