Sickness behavior conserves energy.

“uh so I think the best model interpretation we have of sickness behavior is what you were describing the technical term is you feel sick right and you don't want to move the body you feel cold right which then uh forces you to put covers or you know to to dress to avoid cold environments uh you it it hurts to move your body like to contract muscles and like the the there's alodmia right the sensitiz you become more sensitive to pain all of these things uh likely exist in service of conserving your precious energy budget and even not eating right like follow your appetite.”