Does sleeping fewer hours than needed cause the common cold? If so, how?
There have been some studies directly linking sleep deprivation to increased risk of catching a cold ("Behaviorally Assessed Sleep and Susceptibility to the Common Cold Sleep". 2015;38:1353–9.).
Colds are caused by a family of viruses. There is pretty solid evidence that sleep deprivation has a significant weakening effect on your immune system. Given a weakened immune system, it would be more likely that you would catch a cold if you are exposed to one of the cold-causing viruses.
A new study published in this week's journal SLEEP finds that people who sleep less than six hours are more likely to catch a cold. Researchers tracked 164 healthy men and women for a week at a time, monitoring how much they slept and exposing them to the rhinovirus, also known as, the common cold.
Aric Prather, lead author of the study, and his colleagues found that those who slept less than five hours were 4.5 times more likely to have a cold than those who slept seven hours.
Only 18% of those who slept six or more hours got a cold, while 39% of those who slept less than six hours got the virus. According to the Centers for Disease Control and Prevention, most adults average two to three colds a year and kids have even more. Prather pointed out that when we don't sleep enough, it may impact our immune systems in a variety of ways -- from how the cells act to enabling our inflammation pathways.