Lack of sleep can lower immunity. A new study shows that this results in higher susceptibility to the cold virus.

Summary

Sleep can influence immunity and therefore health. In a new study, those who had less than seven hours sleep a night, or who did not sleep well, were significantly more likely to develop a cold when exposed to rhinovirus. Therefore, aim for around eight hours to stay free of colds.

Introduction

There's a common perception that it's good to have eight hours sleep a night and this might protect from colds and flu. In fact, there's been little scientific evidence to back this up. However, we do know that lack of sleep undermines certain aspects of immunity, like reducing the number of natural killer cells needed to fight infection. However, there is evidence that those getting eight hours sleep a night have lower rates of heart disease than those who get less sleep - and inflammation is a potent factor in heart disease. So it is likely that lack of sleep might increase susceptibility to infection.

What was done

Sheldon Cohen, a long-time researcher in the impact of psychological factors in immunity, of Carnegie Mellon University, Pittsburgh, and colleagues recruited 135 healthy men and women. They asked them about their sleep during a 14 day period - its duration and efficiency (the latter being a measure of the percentage of time spent in bed is actually spent in sleep rather than tossing and turning with insomnia). Then the group was infected with rhinovirus and the number coming down with cold symptoms and developing cold antibodies recorded.

What was found

The less sleep a participant got, the more likely he or she was to develop a cold Those getting seven hours of sleep or less were three times more likely to get a cold than those getting eight hours or more. Sleep efficiency was also a factor with those spending less than 92 percent of their time in bed asleep being five and a half times more likely to get a cold.

What this study means

Poor sleep disturbs the immune system and renders us more susceptible to infection. Colds are not life-threatening (unless complications like a serious chest infection develop), but they can make your miserable and cause an impact in terms of lost productivity - and of course, they are catching! It's easy to neglect sleep in our 24/7 society - but this study shows it can be worthwhile making an effort to get your eight hours if at all possible if you want to ward off colds this winter.

Source

Cohen S, Doyle WJ et al Sleep habits and susceptibility to the common cold Archives of Internal Medicine January 2009;169:62-67