Immunity is a very complex body system that is currently insufficiently studied. This is particularly true of the link with the functioning of other organs and systems. Researchers in the United States have attempted to reveal certain characteristics of the functioning of the immune system as a function of the duration and quality of sleep.

Sleep quality is believed to be an important predictor of the state of immunity, including cold sensitivity. This article examines whether the duration and quality of sleep in the 2 weeks preceding exposure to viruses affect the incidence of a cold.

The study involved 153 volunteers (healthy men and women between the ages of 21 and 55). For 14 consecutive days, study participants reported how long they slept and how effective they were (the percentage of time actually spent sleeping over the total time spent in bed) for the previous night, and whether felt rested after sleep. For this period, the mean scores of each variable evaluating sleep were calculated. Thereafter, study participants were isolated and prescribed nasal drops containing rhinovirus. Researchers monitored the development of clinical manifestations of the common cold (the appearance of objective signs of an infectious disease) one day before and within five days of exposure to the virus.

Researchers assessed the relationship between average sleep duration and cold immunity. Participants who slept less than 7 hours were found to be 2.4 times more likely to develop a cold than to sleep 8 hours or more (95% confidence interval [CI] 1.18-7.30 ). Scientists also assessed the relationship between sleep efficiency and the incidence of rhinovirus infections: study participants with sleep efficiency of less than 92% were 5.5 times (95% CI, 2, 08-14,48) more susceptible to the disease than those whose sleep efficiency was 98% or more. At the same time, the fraction of days that study participants felt rested did not affect the incidence of colds.

The revealed relationship between sleep and the incidence of rhinovirus infection cannot be explained by the titer of specific antiviral antibodies before infection, demographic indicators, season, weight, socioeconomic status, factors psychological or patient lifestyle.

Thus, ineffective sleep lasting less than 7 hours for 2 weeks before infection with respiratory viruses leads to increased sensitivity to colds.