The chronic sleep disorder that afflicts Ravens rookie linebacker Sergio Kindle is a common but often misdiagnosed condition that is treatable and should not affect his NFL career, according to experts in the study of narcolepsy. But the long-term effect is still being studied.
University of Texas football coach Mack Brown disclosed last week that Kindle, 23, suffers from narcolepsy. It is unknown whether the disorder contributed to a recent fall at a house in Austin in which his skull was fractured. But the incident has brought attention to a neurological disorder that many suffer from and few understand.
Typically, those who suffer from narcolepsy can suddenly seem to fall into a deep sleep at any time with no apparent reason.
"These people are extremely sleepy; they have a lot of difficulty maintaining alertness. It's a real problem when they have to do something that demands a lot of focus and concentration," said Dr. Steven Schonfeld, head of pulmonary and critical medicine at Sinai Hospital in Baltimore.
According to the Mayo Clinic, one in 2,000 Americans suffers from the chronic sleep disorder for which there is no cure. Those who have acknowledged suffering from narcolepsy, or were believed to have been afflicted, include late-night talk show host Jimmy Kimmel, Hall of Fame baseball player Hank Aaron and abolitionist Harriet Tubman.
A form of narcolepsy known as cataplexy is often triggered by a strong emotion such as laughter or anger and can result in a loss of muscle tone and slurred speech, leading to temporary paralysis. There is also the possibility of wild or very realistic dreams, known as hypogogic hallucinations, when the patient falls asleep or is very tired.
It is when patients fall abruptly into a deep REM sleep or have cataplexy right before they are injured -- typically from a fall or a car accident -- that experts suspect narcolepsy.
The Ravens acknowledged after Kindle's accident that the team knew of his condition when they made him their first college player takenwith the 43rd pick overall.
Kevin Byrne, the Ravens' vice president for communications, said general manager Ozzie Newsome could not discuss Kindle's situation, citing privacy laws, but added that the Ravens organization was educating itself as it did three years ago after learning that cornerback Samari Rolle had epilepsy, another neurological condition.
"You have to depend on your medical staff for information on something that we don't know about, or don't know well," Byrne said Tuesday. "They're going to give us parameters in terms of whether we should draft a player or, once we get him, the parameters we'll need to work with a player. There is education involved."
A spokeswoman at Breckenridge Hospital in Austin, where Kindle was taken after the fall, said Tuesday night that he was no longer a patient there and referred all questions to the Ravens. Byrne said Tuesday that the team would not comment on the rookie's condition.
Kindle is unsigned, and Ravens coach John Harbaugh has ruled him out of training camp.
Byrne said the only case of narcolepsy he is familiar with in more than three decades in the NFL was former Cleveland Browns coach Bud Carson.
"That was the first time I had heard of it," Byrne said.
Schonfeld said it is often difficult to tell whether a person suffers from narcolepsy or sleep apnea, or simply is sleep-deprived. Because narcolepsy typically is often found in children and young adults, the patient's sleep habits are crucial to the diagnosis.
"It's important to know that they haven't been up for three days," Schonfeld said.
Once diagnosed, Schonfeld added, "it needs pretty close supervision."
Dr. Emmanuel Mignot, a psychiatrist and sleep disorder specialist at Stanford University widely credited with discovering the cause of narcolepsy 10 years ago, said Monday that he has had success treating his patients with drugs.
"I usually can bring my patients back to about 80 percent of what they were before they were diagnosed," Mignot said.
Before he discovered "the code" a decade ago, Mignot said, people with narcolepsy were "often mistreated or misdiagnosed." Patients often went more than a dozen years without proper treatment.
Mignot said a loss of a group of cells in the brain produces a chemical imbalance caused by a lack of hypocretin that can bring on narcolepsy, now considered an auto-immune disease.
Mignot and others believe that narcolepsy can also be triggered by repeated brain trauma. This form is known as "post-traumatic" narcolepsy.
But Mignot said some of his more successful patients are involved in sports. These activities stir brain cells and help the athlete fight the urge to sleep, and also help avoid the excessive weight gain often associated with narcolepsy. He said he encourages patients with narcolepsy to get as much sleep as possible, with naps during the day.
In a 2003 article in The New York Times, Kimmel joked that he often fell asleep at afternoon meetings with his writers. "Not the best way to make people feel good about their material," Kimmel said.
After replacing Brian Orakpo in the Longhorns' defense and having a strong 2009 season, Kindle was projected as a late first-round pick. But he fell into the second round, in part because he had four procedures on the same knee. There were also questions about his off-field activities as a result of a DUI charge in 2007 and a 2009 incident in which he crashed his vehicle into a building and left the scene of the accident.
Kirk Bohls, a longtime columnist for the Austin American-Statesman, said he and others in the local media were surprised to hear about Kindle's narcolepsy.
"It's surprising that it comes up now when he had other issues that might have been related to it," Bohls said Monday.