Misunderstood illness leaves millions exhausted, with most cases undiagnosed

Approximately 3.3 million people in the United States currently have the syndrome, with about one in four people confined to their bed at some point during the illness, according to the Centers for Disease Control and Prevention.

Despite its prevalence, experts say it's a poorly understood condition that physicians frequently miss, with past research suggesting that only about 15% of those affected are diagnosed correctly.

The National Academy of Medicine defines the syndrome as having the following three symptoms that last at least six months.

People may also experience trouble with thinking and memory (often called "brain fog") or lightheadedness when standing up. 

There are no tests to confirm chronic fatigue, so doctors diagnose it by talking to their patients, examining them and excluding other disorders, like hypothyroidism and depression, that often share the same symptoms.

Although hypothalamic dysfunction can trigger dozens of other symptoms, the hallmark signs are insomnia (despite exhaustion), brain fog and widespread pain, the doctor said.

These triggers are usually associated with a gradual onset of CFS, but sudden onset can be caused by certain infections, with two classic ones being COVID and mononucleosis, past research has shown.

There aren't currently any blood tests to uniformly diagnose the syndrome, but Dr. Oh said she is hopeful that will change in the future.

"Instead of finding one smoking gun for the disease, our AI model uncovered a distinct biological fingerprint that was dysregulated in the patients, which spanned changes in gut bacteria, hyperactive immune cells and disrupted metabolism," Oh told Fox News Digital.

Given how differently chronic fatigue syndrome can affect people, there is no universally effective therapy, according to Oh.

The CDC recommends that patients with CFS work with their doctors to create a management plan based on the symptoms that most affect quality of life.

Others may find alternative treatments, like physiotherapy (physical therapy) to be helpful.

Those who experience persistent fatigue that hinders their ability to participate in regular activities or impacts their quality of life should speak with a doctor.