Getting sick is definitely a bummer. But besides feeling icky and being stuck in bed, viral infections may cause us to actually be depressed. While scientists have been clued into this connection for a while, there was little data on how everyday viral infections, like the flu, might mess with our moods.
Note that sickness behavior might be adaptive, helping sick animals clear their infections faster. Lethargy and depression is a very effective way to redirect an animal’s energy away away from everyday expenditure and towards its immune system, where it’s most needed.
Might seem obvious, but the best way to fight off many illnesses is to take a day off and stay in bed. Feeling bad could be just Mother Nature’s way of prodding us to do that.