I’ve been ill for a few weeks and I was fairly sure (in my amateur opinion) that it was related to a significant lack of sleep over the last couple of months. Upon returning to full health I decided to do some quick research on my favourite topic: sleep.
In one recent study looking at sleep habits and resulting susceptibility to the common cold it was found that both sleep length and sleep quality were “important predictors of immunity and, in turn, susceptibility”.
Specifically, “those who slept an average of fewer than seven hours a night […] were three times as likely to get sick as those who averaged at least eight hours”. Furthermore, people who had 92% sleep efficiency were five and a half times more susceptible compared to those with 98% sleep efficiency (defined as the percentage of time in bed actually asleep).
The New York Times article that led me to this study continues:
Sleep and immunity, it seems, are tightly linked. Studies have found that mammals that require the most sleep also produce greater levels of disease-fighting white blood cells — but not red blood cells, even though both are produced in bone marrow and stem from the same precursor. And researchers at the Max Planck Institute for Evolutionary Anthropology have shown that species that sleep more have greater resistance against pathogens.
The more you know… (the more you sleep?)
Update: I’ve briefly mentioned this study on Lone Gunman before, but I think the cognitive impact was the most interesting titbit in that Jonah Lehrer article.