Why do people sleep more when sick?

CBS News

21-02-2025

Despite it being late February, our brutal flu season shows no signs of slowing down. So far this year, more than 6,100 Minnesotans have wound up in the hospital with the flu.
That's the highest number of patients in seven years. Even if it's not the flu, there's a chance you've caught some sort of bug this season.
So why do we sleep so much when we get sick? There's a possible link between rest and recovery.
In north Minneapolis, The Get Down coffee shop is where people come to perk up. But lately instead of being fueled up, many have felt run down, Including the shop's owner Houston White.
"I don't know if it was RSV or COVID or what it was," White said.
It's a shared experience: when people are sick, they get sleepy.
Dr. David Raizen's been snoozing extra too.
"Last night, I slept 12 hours," he said.
The doctor's been sick, but he says what's happening in his body is unknown.
"I wish I understood it. I do research on sleep, but the more I research it, the more I realize we don't really understand it," Raizen said.
Raizen is the go-to on the subject. He did a study using roundworms at the University of Pennsylvania trying to figure out why we sleep while sick.
"The why question is fascinating. The ultimate answer is we don't know for sure why. We don't know why we sleep when we are sick but we also don't know why we sleep on a daily basis. That's one of the great mysteries of biology," Raizen said. "The common wisdom is that we are trying to conserve energy. The degree of energy savings is also not entirely clear."
But does it help the immune system?
"We think it does," Raizen said. "Maybe that immune system that's involved in that innate response is what's optimized during sickness sleep, allows us to fight off infection very rapidly. It's not crystal clear and that keeps me and my collegues in business."