That weary feeling that sets in with an illness is an emotion that helps you fight off infection, researchers say.
Slack facial muscles and drooping eyelids appear early. Exhaustion, loss of appetite, and increased sensitivity to cold and pain come on. Those signs are among a long list of features that researchers have linked to the emotion of being sick, which the authors label lassitude, a now little-used term for weariness from 16th-century Latin.
In a paper in the journal Evolution and Human Behavior, researchers argue that the state of being sick qualifies as an emotion following a review of the literature on sickness behavior, most of which focused on behavioral and physiological changes in nonhuman animals.