Arielle Farber is a virtual prisoner in her own bedroom.
She is trapped there sometimes by a mysterious condition that makes her need to sleep for weeks -- sometimes months -- at a time.
"She has been in bed, for almost four years out of the last 12," said Varda Farber, Arielle's mother.
Arielle Farber has Kleine-Levin Syndrome, a rare neurological disorder that affects basic human needs, primarily a person's urge to sleep.
KLS sufferers feel a need to sleep excessively. As long as KLS sufferers remain in their state of sleep, their sense of time and memory are lost.
Arielle Farber first began showing signs of KLS in 1994, when she returned home to Boston from summer camp and headed straight to bed and stayed there, sleeping almost 23 hours a day.
In the only hour she was awake, her parents said, she acted strangely and seemed confused, reverting to almost childlike behavior.
"We had no idea what she was sick with," said Neal Farber, Arielle's father. "We assumed it was something viral, something bizarre related to maybe in camp."
Then, a week later, Arielle's strange behavior stopped just as suddenly as it had started. The reprieve, however, did not last long.
Six months later, her teenage brother Dani began showing the same strange symptoms, sleeping excessively.
"Twenty-two hours a day is. … I would classify that as almost a 'hibernation,'" Dani said.
Dani Farber underwent several tests, and puzzled doctors could not determine what caused his symptoms.
"We went through all the battery of tests, through EGs and NMRs," Neal Farber said. "They'll try to rule out all of the things that they think about. Is it something related to seizures, brain tumor?"
The Farbers also visited a psychiatrist, who found nothing wrong with Dani.
"Within that first episode, we also went to a psychiatrist," Varda Farber said. "He said, 'There's nothing wrong with [Dani].'"
Mike Rancurello, a pediatric psychiatrist, was also puzzled when another teenage boy came into his unit showing the same symptoms as the Farber teens.
The case was still open a year later, when Rancurello came upon a medical article about KLS.
Both Dani and Arielle Farber were stricken with KLS when their grandfather died.
"The kids were both sick when their grandfather passed away," Varda Farber said. "Imagine waking up from the illness and finding out your grandpa has died."
Over the years, the Farbers have tried -- unsuccessfully -- to help their children with anti-epileptics, anti-schizophrenics and anti-depressants medication.
Heartbroken and frustrated, they helped form a KLS foundation to raise awareness and search for a cure.
"Our challenge here was to find top laboratories, people [who] had an interest and an expertise in these kind of illnesses," Neal Farber said.
Dr. Emmanuel Mignot, director of Stanford University's Center for Narcolepsy, agreed to investigate KLS.
He and his team started by collecting blood samples and patient histories from sufferers all over the world.
"And I hope that in one portion of one chromosome, I will find a big signal that suggests that there is a block of gene that has been passed on to all these patients with KLS," Mignot said.
Until then, for those afflicted with KLS, time keeps slipping away.
Arielle Farber has slept in her second-floor bedroom for more than a year.
She has been sleeping a little less excessively than in her past bouts, but has yet to leave the second floor of her home, or see or speak to anyone beside her parents.
She had planned to attend graduate school when her current KLS episode struck. Those plans -- along with others in her young adult life -- are on hold indefinitely.