Getting a good night’s sleep is supposed to boost your resistance so you don’t get sick as easily. Or put another way, not getting enough sleep puts you at risk of colds and other nuisance infectious diseases. Is this just an old wives’ tale? Apparently not. Or at least, now we can say there’s some evidence to back it up:.
BACKGROUND: Sleep quality is thought to be an important predictor of immunity and, in turn, susceptibility to the common cold. This article examines whether sleep duration and efficiency in the weeks preceding viral exposure are associated with cold susceptibility. METHODS: A total of 153 healthy men and women (age range, 21-55 years) volunteered to participate in the study. For 14 consecutive days, they reported their sleep duration and sleep efficiency (percentage of time in bed actually asleep) for the previous night and whether they felt rested. Average scores for each sleep variable were calculated over the 14-day baseline. Subsequently, participants were quarantined, administered nasal drops containing a rhinovirus, and monitored for the development of a clinical cold (infection in the presence of objective signs of illness) on the day before and for 5 days after exposure. RESULTS: There was a graded association with average sleep duration: participants with less than 7 hours of sleep were 2.94 times (95% confidence interval [CI], 1.18-7.30) more likely to develop a cold than those with 8 hours or more of sleep. The association with sleep efficiency was also graded: participants with less than 92% efficiency were 5.50 times (95% CI, 2.08-14.48) more likely to develop a cold than those with 98% or more efficiency. These relationships could not be explained by differences in prechallenge virus-specific antibody titers, demographics, season of the year, body mass, socioeconomic status, psychological variables, or health practices. The percentage of days feeling rested was not associated with colds. CONCLUSION: Poorer sleep efficiency and shorter sleep duration in the weeks preceding exposure to a rhinovirus were associated with lower resistance to illness. (Cohen S, Doyle WJ, Alper CM, Janicki-Deverts D, Turner RB, “Sleep habits and susceptibility to the common cold,” Arch Intern Med. 2009 Jan 12;169(1):62-7 [Abstract]; h/t Microbiologybytes)
This is a pretty convincing experimental result showing that adults who report lesser duration or less “efficient” sleep more easily develop cold symptoms after intranasal inoculation with rhinovirus. What does this mean? It could well mean that more sleep protects against disease (or less sleep makes you more susceptible), presumably acting through the immune system. We know there are many connections between the nervous system and the immune system, although the mechanisms are poorly understood. Assuming the association is real and not the result of some hidden bias or chance (less likely, given the size of the effect), we don’t know if it is strong enough to protect against (or sufficient to produce increased susceptibility) for other viruses. But it could also mean that people who are more susceptible also sleep less well, that is, poor sleep is a marker for susceptibility, not the cause. Since we don’t know the mechanism we can’t yet predict if using sleeping medication, say, would be beneficial.
Like all research, this opens up other questions, some less easy to answer. This is the kind of experiment you can do with a relatively benign virus like a rhinovirus but not with influenza or some nastier bug. Meanwhile, I recommend a hot toddy to protect yourself against colds. I don’t have any empirical evidence to cite, but I’m willing to volunteer to study the therapy