A good night’s sleep makes a big difference to how we feel, and a new US study suggests that it could also reduce our risk of catching a cold. People who sleep for fewer than seven hours a night were found to be almost three times more likely to get a cold than those who average eight or more hours a night. Having trouble falling asleep or waking up during the night increased the risk even more.
In the study, 54 out of 153 healthy men and women (average age 37) developed cold symptoms in the 5 days after nasal administration of drops containing a rhinovirus. After 28 days, blood samples were tested for antibodies to the virus and it was found that 135 people had become infected, although not all had developed a cold.
For two weeks before being exposed to the virus, the participants were asked each day about the duration and quality of their sleep. In the five days following exposure to the virus, people who had slept for fewer than seven hours each night in the previous two weeks were almost three times more likely to report symptoms than those who had slept for eight hours or more. Broken sleep was found to be even more important: those who were awake for more than 8% of sleep time were five and a half times more likely to show symptoms than those who were awake for 2% or less of the time. Interestingly, the development of cold symptoms did not correlate with how well rested the subjects felt. After taking into account a wide variety of other factors, how long – and especially how well – individuals slept were the strongest predictors of who would develop a cold. Previous research had suggested a link between sleep deprivation and impaired immune function, but this is the first study to show that sleep disturbances can affect susceptibility to cold viruses in normal healthy people. The study is published in the January 12th edition of Archives of Internal Medicine.