Laura Hillenbrand does not keep the pell-mell schedule that one might expect of a newly crowned literary lioness. The author of Seabiscuit: An American Legend, the unlikely page-turner about the ungainly racehorse that became a long-shot champion, is busy consulting on a Seabiscuit movie, which began production in Kentucky this past fall. But to Hillenbrand, 35, who lives in Washington, D.C., “busy” doesn’t mean what it does to most people. To her it means talking on the phone. She receives scores of invitations every month to appear at bookstores or give speeches or write articles—and declines almost all of them. On some days, she doesn’t have the strength to leave her house, and therein lies another tale of long odds, perseverance and unexpected fame.

Hillenbrand is afflicted with chronic fatigue syndrome, a disorder marked by physical and mental exhaustion, recurring aches and fleeting fevers. She came down with it 15 years ago—remembers the day it struck, in fact—and was bedridden off and on for six years. She toiled on Seabiscuit for four years, often keeping a box of breakfast cereal close at hand so she wouldn’t have to waste precious energy walking to the kitchen, sometimes writing (in longhand) with her eyes closed to stop the vertigo. The book, a chronicle of the racetrack world of 1930s America, has so captivated readers (the hardcover was a No. 1 New York Times best-seller last year, and the paperback remains on most best-seller lists) that the news of what she overcame to create it has transformed Hillenbrand into a leading spokes-person for victims of chronic fatigue syndrome, or CFS.

“As I lay in bed over the years, I wished that somebody prominent would go out and make an articulate case for CFS patients,” she says. “So when Seabiscuit’s success gave me the opportunity to take on that role, I thought, OK, that’s what I’m going to try to do.”

To people with the disorder, many of whom have been misdiagnosed or even stigmatized as malingerers, Hillenbrand’s candor has been a godsend. “Laura has told her story so graciously and compellingly,” says Kim Kenney, head of the Chronic Fatigue and Immune Dysfunction Syndrome Association of America, a patients’ group. “Her triumph has not only inspired patients but has really made a difference in helping the public understand what people with this illness have to go through.”

Hillenbrand’s willingness to serve as the poster child for chronic fatigue syndrome coincides with other welcome developments, including new thinking about its causes. Though a cure for the syndrome does not exist, researchers have recently amassed evidence that counseling and supervised exercise therapy can often help patients. Perhaps most impressive, medical researchers at the U.S. Centers for Disease Control and Prevention in Atlanta are working on the first test for screening and possibly diagnosing the syndrome. Says Dr. William Reeves, who directs chronic fatigue syndrome research at the CDC: “The field is progressing quite rapidly.”

It all began for Hillenbrand the evening of March 20, 1987. She was then a sophomore at KenyonCollege in Gambier, Ohio, a straight-A student with hopes of becoming a history professor. She had always been active, riding horses since age 5, swimming competitively (100-meter backstroke) in her suburban Maryland high school, biking and playing tennis in college. She’d eaten at a restaurant that day, and by nightfall was doubled over with pain—food poisoning, she figures. “I was so sick we called paramedics,” she says. For three weeks she was miserable, then awoke and couldn’t sit up. “Even if the building had been burning down, I wouldn’t have been able to get out of bed,” she says. She returned home to Bethesda, the Washington, D.C. suburb where she grew up, and spent the next two years virtually bedridden.

Frustration with medical practice is a frequent side effect of chronic fatigue syndrome, and Hillenbrand would see seven internists and numerous specialists who attributed her illness to Epstein-Barr virus infection, a sinus infection, bulimia and, though she was 20, the onset of puberty. Some said the problem was all in her head. “‘Couldn’t handle school so dropped out,’” she says one physician noted. Looking back, Hillenbrand says she doesn’t blame the doctors for not identifying her illness, given that so little was known about it at the time. “But I do blame them for making assumptions about my character and implying that I was somehow responsible for this illness.”

Finally, a physician at the Johns Hopkins University School of Medicine in Baltimore diagnosed her correctly. She recovered somewhat and started working as a freelance magazine writer, often covering horse racing. In some ways, her experience was typical: about half of chronic fatigue patients recover significantly within the first five years of succumbing, according to the CDC. Overall, though, Hillenbrand’s illness has been more severe than most cases, she says. In 1991, she had a relapse, becoming even sicker than before. “I spent two straight years lying in bed staring at the ceiling,” Hillenbrand says.

In nearly two decades of searching for the cause of chronic fatigue syndrome, researchers have turned up no definitive answer; some believe that the disorder has multiple causes, perhaps as heart disease does. But there are leads. The 1980s-era theory that chronic fatigue syndrome was caused directly by the Epstein-Barr virus, the infectious agent behind the fatiguing disorder known as mononucleosis, has turned out to be partially true. That virus and others seem to play an indirect role in the disease. In a study of 250 Londoners with either mononucleosis or an upper respiratory tract infection, 9 percent of the mono patients were diagnosed with chronic fatigue syndrome six months after first becoming ill, whereas none of the patients with upper respiratory tract infections developed the affliction. The study, led by researchers at St. Bartholomew’s Hospital in London and published last year in the Lancet, is the first conclusive evidence that a viral infection can trigger chronic fatigue syndrome.

In addition to infectious mononucleosis, studies suggest that two other infectious illnesses—Q fever and RossRiver virus—can lead to chronic fatigue syndrome. To learn more about the risk factors that make people susceptible to chronic fatigue syndrome, the CDC is funding a study that will track patients in the Australian state of New South Wales who contract Q fever, RossRiver virus or infectious mononucleosis.

But infectious agents may not be the only culprits. Peter Rowe, a pediatrician and director of the chronic fatigue syndrome clinic at Johns Hopkins Children’s Center, has documented that some young people who developed the syndrome also have a disorder called neurally mediated hypotension; their blood pressure plunges after they’ve been standing for several minutes, leading to dizziness, weakness and, over time, exhaustion. Other medical researchers have failed to find the same link between bouts of low blood pressure and chronic fatigue syndrome, but Rowe remains convinced it’s a factor in some cases and says he has given such patients blood-pressure-regulating drugs with good effect. Likewise, Rowe and other researchers have argued that a heart rate abnormality, postural tachycardia syndrome, in which a racing heart causes light-headedness, may also be involved in chronic fatigue syndrome.

Even though the disorder has been recognized only fairly recently as a clinical entity—the CDC officially defined chronic fatigue syndrome in 1988—it probably isn’t new to humanity. Physicians and historians of medicine say it closely resembles neurasthenia, a so-called nervous exhaustion that was one of the most commonly diagnosed conditions in the United States and Europe in the second half of the 19th century.

“If you read the descriptions of neurasthenia in 1880 in journals, textbooks and the diaries and letters of patients, you would be in no doubt that what they’re describing is chronic fatigue syndrome,” says Dr. Simon Wessely, a London psychiatrist and coauthor of the 1998 book Chronic Fatigue and its Syndromes. But neurasthenia, originally thought to be caused by infection or overwork, fell out of favor as a diagnosis before World War I, largely because doctors failed to find a concrete reason for it.

Historically, says DePaul University psychologist Leonard Jason, physicians have treated many mysterious chronic illnesses as psychological problems. For example, some experts once thought multiple sclerosis was caused by “stress linked to oedipal fantasies,” he says. “But later, with the development of sophisticated imaging technologies, researchers showed clearly that MS is a neurological disease that has a physical cause.” Similarly, he predicts, advances will reveal that “physical causes also underlie most cases of CFS.”

One of the most surprising findings is that chronic fatigue syndrome appears to be 100 times more common than many experts previously believed. In a study led by DePaul’s Jason, researchers surveyed some 18,000 people in Chicago by phone, then gave medical exams to respondents who reported chronic fatigue symptoms: 4 out of every 1,000 people surveyed had the affliction, leading to an estimate of more than 800,000 cases nationwide. And contrary to the stereotype of the disorder as an affliction of well-to-do young whites—“the Yuppie flu,” it was once dismissively called—the researchers found that the syndrome was most prevalent among the minorities and lower-income people surveyed. Also, nearly two out of three cases had no prior history of psychiatric problems, contradicting the widespread view that chronic fatigue syndrome is really just a symptom of an underlying mood disorder such as depression or anxiety. A notable feature of the disorder’s prevalence is its pronounced sex bias. More than two out of three chronic fatigue patients are women. Researchers don’t know why.

It’s perhaps not surprising that Hillenbrand, leveled by chronic fatigue syndrome, would relish delving into Thoroughbred racing, a world of explosive energy and thunderous speed. And Seabiscuit is, above all, a story of redemption. The horse toiled in claiming races—the lowest rung on the racing ladder—until a laconic, former mustang breaker named Tom Smith saw something special in the squat animal and trained him to become one of the greatest racehorses of the century. Seabiscuit’s owner, Charles Howard, was a San Francisco bicycle repairman who became a millionaire car salesman. And a half-blind, flat broke and presumably washed-up Canadian named Red Pollard rode the race horse into history. In 1938, Seabiscuit was America’s leading newsmaker, beating out President Roosevelt and Mussolini in total inches of news stories devoted to him.

“Here was a story I could get lost in, with fascinating subjects whose lives were complicated and vigorous—everything my life wasn’t,” says Hillenbrand. “Writing it helped me redefine myself, to become Laura the author instead of Laura the sick person. That was very rewarding.”

Over four years, she did little besides work on the book. Each day, she meted out her limited store of energy, calculating whether a trip to the pantry or the bathroom was worth the expenditure. Her morning shower flattened her, she says. In her small home office, she kept everything within arm’s reach, including a small refrigerator. Still, she did 150 phone interviews, transcribing each one herself.

In a passage of Seabiscuit that seemingly betrays the presence of the author’s own struggles, Hillenbrand writes that “for all its miseries, there was an unmistakable allure to the jockey’s craft,” and goes on to say: “Man is preoccupied with freedom yet laden with handicaps. The breadth of his activity and experience is narrowed by the limitations of his relatively weak, sluggish body. The racehorse, by virtue of his awesome physical gifts, freed the jockey from himself. . . . For the jockey, the saddle was a place of unparalleled exhilaration, of transcendence.”

Writing Seabiscuit was Hillenbrand’s transcendence. And like the once-downtrodden Thoroughbred, she became a star. Critics poured praise on the book, which became an instant best-seller, garnered awards and was celebrated as one of the favorite books of 2001.

But her success came at a price. “The day after I turned in my manuscript, my health collapsed,” says Hillenbrand. “You want so much to defy this illness and live on your own terms. I hoped I could get away with it, but I couldn’t.” Debilitating symptoms of chronic fatigue, and the devastating vertigo that accompanied them, had returned with a vengeance.

Medical researchers have long sought a reliable diagnostic test for chronic fatigue syndrome, which a physician can identify only after ruling out the many other possible causes of severe fatigue. Now CDC researchers may be on the verge of developing such a test, based on analyzing patients’ genetic material.

Essentially, the researchers have found that chronic fatigue syndrome prompts a complex physiological response that leads to a telltale pattern in gene output. They extracted from the patients’ blood cells the intermediate genetic material known as messenger RNA, which is produced when genes are instructing cells to grow, divide, fend off an invader or otherwise be active. Using a recently developed technology called gene expression microarrays, the researchers tested the patients’ RNA, inferring from it which genes had been active—that is, “expressing” their genetic code, as scientists say. The technique enables scientists to probe for tens of thousands of genes simultaneously and determine which ones are active, or “on,” and which are inactive, or “off.” Chronic fatigue syndrome, the CDC researchers speculate, might yield a sort of genetic signature, a pattern of the genes’ expression.

Analyzing blood samples from chronic fatigue syndrome patients and healthy people in the Atlanta area, the researchers posed a simple question: Could the genetic tool tell the difference between the samples? “The answer is: yes, it can,” says Suzanne Vernon, a molecular epidemiologist and the study’s lead researcher. She cautions that more work is needed to confirm the findings in other populations, for example. But she says the results are “very exciting,” and she predicts that microarrays will someday routinely diagnose chronic fatigue syndrome, whatever the underlying cause.

“Most CFS experts would agree that there may be several subcategories of [the disorder]—due to an infectious agent or to stress and so forth,” says Vernon. “I anticipate seeing an underlying gene-expression pattern common to all CFS patients but, in addition, some unique genes expressed that correspond to each subgroup.”

Treatment research has recently focused on two behavioral therapies, one for the mind, another for the body. In graded-exercise therapy, patients, under supervision, are encouraged to gradually increase their activity level—beginning with a two-minute walk, for example, and then lengthening their workouts by a couple of minutes each day. The idea is to increase stamina without risking the overexertion that can be so devastating. Three studies on graded-exercise therapy, all published since 1996, found that many patients participating in exercise programs felt better, and some even regained their former levels of physical activity.

At Johns Hopkins, Rowe noticed that many of his chronic fatigue syndrome patients had unexpected stiffness and a limited range of movement. So on 100 or so of them, he says, he has tried manual therapy in which a physical therapist gently moves a patient’s limbs and body to restore normal movement before encouraging her to resume physical activity. “As the patients’ mobility has increased,” he says, “their symptoms have diminished, and many of them now can even exercise without suffering relapses.”

The other approach is cognitive behavioral therapy—counseling that focuses on the psychological and social problems that patients often develop while trying to cope with the affliction, including depression, frustration, social withdrawal and feelings of helplessness. Cognitive behavioral therapy aims at helping patients gain control over their symptoms.

Wessely, the London-based psychiatrist and author, says graded-exercise therapy and cognitive behavioral therapy have helped some chronic fatigue patients for many months and even years beyond the initial treatment period. “They’re the best treatment approaches that we have now,” he says.

But some patient advocates have criticized the behavioral approach, saying it trivializes the affliction as psychological in origin. Kenney, of the CFS patients’ group, cautions that patients can’t just exercise the disorder away and may harm themselves if they carelessly try to do so. Wessely points out that the behavioral treatments have also helped people with clearly physical illnesses such as cancer and arthritis and insists that whether the cause of chronic fatigue syndrome is physical or psychological doesn’t matter.

“We always tell patients truthfully that we don’t know what caused their [chronic fatigue syndrome]—maybe they were stressed, maybe it was a virus. We say it’s like being in a hit-and-run accident: it’s happened, and that’s tough. Now, what can we do about it? We know that psychological factors such as depression can affect the outcome and so can physical factors like inactivity. And those we can change.”

Hillenbrand has begun seeing a therapist who takes a cognitive behavioral approach. “We’re talking about how I’m perceiving the illness and what my expectations are,” she says. “I don’t think I went into the illness with these problems, but over the years of being traumatized by chronic fatigue syndrome, you develop problems that make it harder for you to recover from it. I’m feeling a bit better, and I think ultimately the treatment will help me.”

What she’d really like to do—work on another book—isn’t possible just now. “I absolutely destroyed myself in finishing Seabiscuit, and my ability to read and write is severely limited” because of chronic vertigo, she says. “I have ideas that I’m itching to turn into books, but I can’t touch them.”

Hillenbrand knew from the outset that writing Seabiscuit would jeopardize her health, but she has no regrets: “Whether it ruins me for good, writing this book was absolutely worth it. Every morning I woke up happy because I knew I was going to spend the day with these men and with this horse.”