Of all the classic Covid symptoms (the dry cough, the stinging throat, the achiness), fatigue may be one of the most debilitating, persistent and confounding.
Dr. Marc Sala, co-director of the Northwestern Medicine Comprehensive Covid-19 Center, said fatigue has become the dominant complaint from his patients. That could be because Covid symptoms are becoming milder overall — he no longer regularly sees patients with severe respiratory damage, and so fatigue has come to the forefront, he said. It’s also possible that fatigue could be a more common symptom with the newer variants, he said.
Some degree of Covid-related fatigue is expected. When someone is in the acute phase of a Covid infection, “the body is really busy fighting its war against the virus” and tries to conserve energy, said Dr. Ziyad Al-Aly, the chief of research and development at the V.A. St. Louis Healthcare System. “You don’t want to do anything — you want to sit in bed,” he added.
But it’s somewhat of a mystery why some people experience really intense fatigue during an infection — the kind that leaves them flattened on the couch, unable to even watch T.V. or heat up soup — while others merely feel drained. It’s also not yet clear why extreme fatigue persists in some people months after they test negative, a hallmark of long Covid.
Doctors have seen a spectrum of fatigue associated with Covid: Some people are wiped out after they exert themselves, whereas others experience more constant exhaustion, said Dr. Paul Auwaerter, a professor at the Johns Hopkins University School of Medicine.
“I don’t think we really understand it,” said E. John Wherry, director of the Institute for Immunology and Immune Health at the University of Pennsylvania Perelman School of Medicine. “There’s a lot of speculation.”
Why Covid might cause fatigue
One hypothesis for why people can feel so exhausted is that Covid may disrupt the mitochondria — what Dr. Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco, calls the Energizer bunnies of our cells. Mitochondrial dysfunction can slow down the body, he said, and this can last beyond the acute phase of an infection.
Sleep disturbances may also contribute to overall fatigue during and after an infection, as Covid makes it harder to get a good night’s rest.
Another theory, specifically related to long Covid, is that the virus may linger in the body even after someone tests negative, Dr. Al-Aly said. After an infection clears, the body should flip an “off switch,” he said, signaling that it no longer needs to fight off the virus. But in people with long Covid, he said, the body stays in defense mode, continuing to conserve energy.
New research published Monday points to an additional potential cause: People with long Covid seem to have significantly less morning cortisol, the hormone that gets you “up and going” when you wake up, Dr. Chin-Hong said. Cortisol deficiency, in general, can lead to fatigue.
Researchers are still trying to untangle why some people develop long Covid and not others. “That’s really the great puzzle,” Dr. Al-Aly said.
Potential remedies
There is no established protocol yet for resolving fatigue, but “The basic rule is rest,” Dr. Al-Aly said. “You don’t want to fight it.”
During an active infection, listen to your body: Take it easy as much as possible and make sure you are adequately replenishing fluids.
If intense fatigue persists for more than 30 days after you test negative, Dr. Al-Aly advised talking to your primary care doctor sooner rather than later to figure out a course of action.
For people with long Covid, getting enough sleep is vital, said Dr. Fernando Carnavali, site director of the Center for Post-Covid Care at Mount Sinai Doctors, Ansonia. Fragmented or insufficient sleep can exacerbate exhaustion. It is important to follow the fundamentals of sleep hygiene: Try to fall asleep and wake up at consistent hours, keep your bedroom dark and cool, avoid alcohol too close to bedtime and carve out time to unwind before you shut your eyes.
People with fatigue related to long Covid should also be careful about exercise, Dr. Carnavali said, starting slow and very gradually building back exercise tolerance.
If you are struggling with fatigue, recognize that you may have a new baseline, Dr. Carnavali said. He advises his long Covid patients to keep a journal over a two-week period to track how they feel after doing everyday activities — maybe a wave of fatigue hits after dinner with friends, or you find it difficult to read for an hour. Understanding these correlations can help prevent you from pushing yourself too hard. Dr. Carnavali also said reframing is important: “I cannot do 10 miles; I will do half of that. I cannot do dishes for half an hour; I will do them for five minutes.”
“You have to define new baselines in order to adapt,” he said. The extreme fatigue associated with long Covid “may go away — some people are getting better, and this is just great to see,” he said.
But “There are new patients every week,” he added.