It’s just a cold. But even though I know I’m not horribly ill, I feel this overwhelming need to skip work, ignore my family and retreat to the far corner of the sofa.

I’m not being a wimp, it turns out. Those feelings are a real thing called “sickness behavior,” which is sparked by the body’s response to infection. The same chemicals that tell the immune system to rush in and fend off invading viruses also tell us to slow down; skip the eating, drinking and sex; shun social interactions; and rest.

“Those messages are so powerful they can’t be ignored,” says Philip Chen, a rhinologist at the University of Texas Health Science Center at San Antonio. But that doesn’t mean we don’t try. Symptoms like a stuffy nose are obvious, Chen notes, but we’re less aware that changes in mood and behavior are also part of our bodies’ natural response to infection.

It might behoove us to pay attention. There is plenty of evidence that having a cold impairs mood, alertness and working memory and that brain performance falls off with even minor symptoms.

But for most people, having a cold does not equal “take the week off.” And that means many people work sick, even when it can put others in danger. To read more from NANCY SHUTE, click here.