If you’re constantly tired, even after a good night’s sleep, scientists think there could be a little-understood reason.
For the first time, NIH-funded scientists have found that chronic fatigue syndrome (CFS) is seven and a half times more common in people infected with Covid.
About one in 20 Americans who have had the virus have this condition, which causes exhaustion after performing simple tasks, orthostatic intolerance (dizziness when standing), poor sleep, cognitive decline and fatigue.
Since virtually all Americans have had Covid, researchers said there could be millions of new cases of undiagnosed chronic fatigue syndrome.
There is no cure for chronic fatigue, but doctors can try a number of medications to combat the symptoms, including antidepressants and mood stabilizers, as well as physical therapy and psychotherapy.
Chronic fatigue syndrome is diagnosed by a doctor by reviewing your medical history, doing a physical exam, and ruling out other possible conditions. Currently, no test alone can definitively diagnose the condition.
Researchers found that Covid infections can increase the chances of developing chronic fatigue syndrome.
Dr. Suzanne Vernon, director of research at the Bateman Horne Center and lead author, saying: ‘This research underscores the urgency for healthcare providers to recognize ME/CFS post-COVID-19.
“Early diagnosis and proper management can transform lives.”
The most common symptom was post-exertional malaise (PEM), reported by almost 16 percent of patients with acute infection and 29 percent of people who had recovered from the infection.
An estimated 3.3 million Americans suffer from chronic fatigue syndrome, also called myalgic encephalomyelitis (ME), a long-lasting disorder that causes exhaustion, brain fog and pain for six months or longer.
The research was part of the NIH’s COVID Research to Improve Recovery (RECOVER) initiative, which aims to better understand, diagnose and treat long Covid.
Chronic fatigue is thought to be the result of the body fighting an infection with all its might, causing the immune system to go into overdrive and then remain in overdrive when it is no longer needed.
Around 11,800 people included in the study had been infected with Covid, while just over 1,400 had not.
The researchers published questionnaires every three months from October 2021 to September 2024.
Of people who had been infected, 4.5 percent met the requirements for chronic fatigue syndrome, compared to 0.6 percent of patients who had not been infected with Covid.
Nearly 40 percent were “ME/CFS-like,” meaning they had at least one symptom of the condition, and about 56 percent reported no symptoms of fatigue.
Forty-five percent of people who met the criteria for chronic fatigue were also identified as some of the most symptomatic long Covid patients, underscoring the overlap between the two conditions.
The most common symptom was post-exertional malaise (PEM), reported by nearly 16 percent of infected patients and 29 percent of people who had recovered from the infection.

Chronic fatigue syndrome is a life-altering condition. About 75 percent of people who suffer from it cannot work.
Orthostatic intolerance (dizziness when standing) was the second most common: 14 percent of those infected and 25 percent of those post-infected reported it.
Other symptoms such as restful sleep, cognitive impairment and fatigue were more common in post-infected participants. All symptoms were less frequent in uninfected participants compared to those who had been infected.
The research was published in the Journal of General Internal Medicine.
The prevalence of chronic fatigue may be increasing, the researchers said, noting that before the pandemic, an estimated 0.2 to 1 percent of Americans were living with CFS.
A national survey conducted throughout 2021 found that about 1.3 percent of American adults had been diagnosed with chronic fatigue syndrome by a doctor, suggesting to researchers that post-COVID CFS cases may be already increasing the number of people affected throughout the country.
Fatigue is common among people suffering from long Covid, an amorphous condition made up of a constellation of symptoms ranging from brain fog and fatigue to heart inflammation and joint pain.
It is a life-altering condition. About 75 percent of people who suffer from it cannot work.
CFS causes fatigue, sleep disturbances, brain fog/difficulty thinking, dizziness and orthostatic intolerance (the medical term for when standing causes symptoms), headaches, muscle weakness and pain, and more.
Your browser does not support iframes.
It can be difficult to diagnose because symptoms can change in how often they occur and their severity can change over time.
The most common symptom is post-exertional malaise or worsening symptoms after doing something physical or mental.
Everyday activities like showering, driving, reading, and even talking can trigger PEM, making normal tasks exponentially more difficult.
ME/CFS is still understood as a multisystem condition that affects multiple parts of the body. However, the pandemic has increased attention on how Covid can trigger or worsen it.
Several studies have highlighted an overlap in symptoms reported by patients with long COVID and ME/CFS.
An estimated 17 million Americans have long Covid, which manifests differently in each person.
Some people may only experience shortness of breath and fatigue, while others may only experience brain fog and difficulty concentrating.
For this reason, diagnosing long Covid is challenging.
Your browser does not support iframes.
Two years ago, American, Danish and British researchers concluded that long Covid has been “greatly exaggerated”. Shortly after, another UK-based scientist acknowledged that the condition is real, but argued that more patients have been labeled with it than actually have it.
Last week, a new study found that some patients who received a 15-day course of Paxlovid, the drug used to treat Covid, experienced significant improvements in symptoms that had plagued them for years.
Five of 13 patients (38 percent) showed sustained improvement, but almost all benefited temporarily.
Dr. Michael Peluso, principal investigator of UCSF’s long Covid research program, said: “If we’ve learned anything over the past four years, it’s that long COVID is complex and figuring out why some people benefit so markedly from antiviral treatment while others are not one of the most important questions for the field.
“We’re going to need to come to terms with that complexity to get answers for the millions of people who suffer from this condition.”