Sleep and the Common Cold

Getting plenty of sleep is one of the best ways to stay healthy during cold and flu season.

In a study published in the Archives of Internal Medicine, researchers in Pittsburgh studied the effects of sleep on immunity. For  two weeks, 153 healthy women and men between the ages of 22 and 55 reported their sleep duration (how many hours they slept each night), their sleep efficiency (the percentage of time they spent in bed asleep), and whether they felt rested the following morning. After the two weeks, they were exposed to a common cold virus.

Researchers found that more sleep the people had before they were exposed to the cold virus, the higher their resistance to infection. Adults who slept less than 7 hours were almost 3 times as likely to develop a cold, compared to those who slept 8 hours or more.

Sleep efficiency was also a factor. Participants who reported less than 92 percent efficiency were five and a half times as likely to come down with a cold compared to those whose efficiency was reported to be 98 percent or above.

How does sleep make our immune systems stronger?

Sleep can actually turn our genes on and off. It doesn't change our genetic code, but studies show that it does change how our genes are expressed, which determines how our bodies, including our immune systems, work. Other research has found that lack of sleep can suppress the immune system by inhibiting activity of "natural killer" white blood cells on patrol for viruses and bacteria (and cancer cells).

Getting more sleep during cold and flu season can reduce your risk of infection, but the benefits don't end there. Studies show that adequate sleep can also improve learning and memory, reduce inflammation, and decrease the risk of cardiovascular disease, diabetes, hormone imbalances, autism, and Alzheimer's disease.

References:

Cohen S et al. Sleep habits and susceptibility to the common cold. Archives of internal medicine, 169(1):62-7, January 2009.

Fondell E. et al. 2011. Short natural sleep is associated with higher T cell and lower NK cell activities. Brain, Behavior, and Immunity 25(7):1367-75.

Mullington J.M. et al. 2009. Cardiovascular, inflammatory, and metabolic consequences of sleep deprivation. Progress in Cardiovascular Diseases 51(4):294-302.

Van Cauter E. et al. 2007. Impact of sleep and sleep loss on neuroendocrine and metabolic function. Hormone Research 67 Suppl 1:2-9.

Wang G. et al. 2011. Synaptic plasticity in sleep: learning, homeostasis and disease. Trends in Neuroscience 34(9):452-63.