New research on chronic fatigue syndrome has shed light on possible causes for this mysterious illness, and has given hope to the millions of people believed to suffer from the disease worldwide.

Behind chronic fatigue syndrome's benign name is an illness that can ruin the lives of once healthy people, leaving them in a near-permanent state of exhaustion and sometimes unable to work, think clearly or care for themselves.

"It was like being buried alive," Samantha Miller, a former sufferer of CFS, told jouralist Jo Marchant for her book Cure published last year. "I was exhausted, with terrible joint pains. It was like having flu all the time with no certainty of recovery. I couldn’t do anything. I was trapped."

Illnesses resembling chronic fatigue syndrome have been described under various names dating back centuries, but despite its long history, doctors have had little luck in nailing down a cause for this crippling disorder, much less effective treatments. Chronic fatigue syndrome leaves no visible physical impairments, leading many people in the past to label it a psychosomatic disorder, or even dismiss it as "yuppie flu" or "female hysteria."

In recent years, however, activism by patients and their families has fueled greater recognition of CFS as a real illness that should be studied and cured. Much of that activism has focused on replacing "chronic fatigue syndrome" with the older, less stigmatized (though questionably accurate) name "myalgic encephalomyelitis," which means "brain and spinal cord inflammation with muscle pain." The illness name is often shortened to ME/CFS. Activists have also pushed to get funding from the National Institutes of Health to research the illness.

Now, that push finally is starting to pay off. Research published this week in the journal Proceedings of the National Academy of Sciences gives the first solid clues to what lies behind ME/CFS: a person's own immune system.

“What is at stake here is ‘proof of concept’ that this disease is real,” lead author Jose G. Montoya of Stanford University tells Lisa Rapaport of Reuters. “Patients have been humiliated, ostracized, and ignored.”

After comparing the blood of nearly 200 ME/CFS sufferers to nearly 400 healthy people, reports Giorgia Guglielmi of Science, Montoya's team found that the levels of 17 different cytokines, small proteins that immune cells use to communicate with each other, found in a victim's blood appeared to correlate with the intensity of their ME/CFS symptoms.

These immune system imbalances haven't appeared on the routine blood tests used by most doctors and researchers because those blood tests weren't looking for the correct kinds of inflammation, reports Miriam Tucker for NPR.

"Inflammation is much more complicated than two imperfect old measures," Montoya tells Tucker. "We're showing an inflammation that has not been seen before."

Researchers hope that this discovery will drive the development of a conclusive blood test for ME/CFS, reports Tucker, and guide research into treatments for the illness. Already, Tucker reports, researchers in Norway are doing trials with an immune drug that has been found to relieve some symptoms of ME/CFS. And another team of researchers at Stanford University, led by a geneticist whose son is a victim of ME/CFS, is hoping to use "big data" to develop treatments for the illness.

"This is a field that has been full of skepticism and misconception, where patients have been viewed to have invented their disease," Motoya tells Tucker. "These data clearly show the contrary, and demonstrate what can be achieved when we couple good research design with new technology."