A study of 153 individuals that assessed sleep habits and then exposed them to a controlled dose of common cold virus. 88% became infected, but those who averaged less than 7 hours of sleep per night had the highest risk for colds  Those with a “sleep efficiency” (ie proportion of time spent in bed actually sleeping) of less than 85% had the highest risk for developing a colds. See the original article here.

Dr Ramesh Manocha