A good night’s sleep may be one way to fight off a cold. In one study, adults who slept less than seven hours a night had triple the risk of catching a cold compared to those who slept more than eight hours. Researchers interviewed participants in the study about their sleeping habits, and then dosed them with nasal drops containing one of the viruses responsible for the common cold. The virus took hold more readily in those who were less rested; suggesting that lack of sleep may have weakened their immune systems.
Source: Archives of Internal Medicine, Vol. 169, pg. 62