There was nothing sweet about Kaitlyn Terrana's 16th birthday. And she has virtually no recollection of her last birthday, her 17th, either. She slept through both of them.

At a time when the teenager should be living each day to the fullest, she is trapped in a roughly six-week cycle in which she has no choice but to take to her bed, slumbering for about 10 days at a time.

Kaitlyn has developed an extremely rare condition called Kleine-Levin syndrome, or KLS, and it is stealing her life away.

"Kind of like the day before, I start feeling really tired and it's really hard for me to focus in class," she says from her home in Winona, Ont., near Hamilton. "And then after that, I'm just gone for 10 days. I have to sleep, I can't stay awake."

'It's almost like she's a walking zombie. She's in a complete fog'—Kathy Terrana

Her mom, Kathy Terrana, has to closely monitor Kaitlyn when she experiences one of these sleeping periods, saying her daughter can't be left alone.

"In the beginning of her episodes, she starts off being very, very tired," she says. "By late evening I can usually tell that, yes, she is starting an episode, because she doesn't talk, she doesn't converse with anybody.

"It's not very nice to say, but it's almost like she's a walking zombie, because when they're in their episodes they can be walking around but they don't know what's going on around them. So there's no empathy, there's no feeling whatsoever. She's in a complete fog."

20-hour stretches of sleep

Once an episode starts, Kaitlyn can easily sleep 20 or more hours at a stretch, says Terrana, who periodically wakes her daughter to take her to the bathroom, give her liquids and food.

But those meals must be carefully controlled because of another characteristic of Kleine-Levin syndrome -- a voracious appetite.

"I monitor her food intake because otherwise she will walk to a cupboard and just binge on anything that's available," says Terrana. "It's like they're in a starving mode when they wake up. They just eat anything and everything in sight."

Kaitlyn knows her mom wakes her up to use the bathroom and to eat and drink, but she doesn't remember anything about those times away from her bed, even though she's supposedly awake.

"It's kind of like a dream," she says, struggling to put words to the feeling. "If you look back into your dreams, you remember certain things but not everything. It doesn't connect. That's how 10 days of my life is.

"So you look back and it's all foggy and it doesn't make sense."

No treatments, cure

Little is known about KLS because the condition is so rare. Doctors don't know what causes it and there are no treatments or cure.

The syndrome affects at least twice as many boys as girls and onset is usually during adolescence. Typically, the episodes last from 10 to 15 years, then disappear as mysteriously as they began.

Kaitlyn had her first attack two years ago when she was 15 and in Grade 10.

"Basically, I started feeling really weird. I felt really off. I couldn't focus in school," she recalls of that month-long first attack.

"Then out of nowhere I came out of it and I was back to normal. Basically, it felt like I was drugged for an entire month. I was confused about a lot of things. I looked at my (school) notes and my notes weren't written properly. And my notes are always neat and I always write everything down.

"Right away I knew something was really, really wrong. That's not me at all."

Initially, her mom thought her excessive sleepiness might be the result of depression. She tried to get her out of bed to go to school. She encouraged her to go out with friends.

"I didn't know what she had. I thought she just didn't want to talk," she says.

Difficult to diagnose

Terrana took her daughter to a therapist. She was also seen by doctors, who diagnosed her with partial complex seizures, one of the neurological conditions that has characteristics that mimic but don't fully match KLS.

She was prescribed a number of drugs — antidepressants as well as sleep and antiseizure medications — but they made Kaitlyn worse, her mother says.

It wasn't until she saw Dr. David Callen 18 months after her first episode that Kaitlyn got her KLS diagnosis.

"There's a couple of reasons why it's so difficult to diagnose, first because it is so rare, it's only like one in a million," says Callen, a pediatric neurologist at McMaster University's Children's Hospital in Hamilton.

"And secondly, there are no diagnostic tests, so we can't do an MRI and say 'Oh yeah, you have Kleine-Levin syndrome.' We can't do blood work and say 'Oh, yeah, you have the factors associated with this.' There have been tests that have been looked at, but there really is nothing that has been shown to be useful in actually making a diagnosis."

Callen says the diagnosis is based on a combination of specific symptoms that occur with excessive sleepiness, among them compulsive eating, cognitive and mood disturbances or hypersexuality, the latter mostly experienced by males with the condition.

While some patients recall having had a flu-like illness before their first episode, Callen says there is no evidence to support a theory that KLS might be an autoimmune disorder.

The syndrome's cause and its decade-plus duration remain a mystery.

"Often these episodes cease in their third or fourth decade of life," he says of those afflicted. "It can be a long time and the episodes can last for days and they are very disruptive."

Missing out on school, social life

Indeed, one of Kaitlyn's biggest worries is that she is missing so much school. This semester she is taking only a couple of Grade 12 classes and has given up the idea of going to university next year along with her classmates.

"It's affecting my schooling greatly because even though the school tries to accommodate me as much as they can, it's still difficult for me because I miss 10 days at a time and I have to catch up on what I missed plus the lessons I'm learning in class," she says.

"By the time I get caught up, it happens again, which is very stressful."

Kaitlyn's dream is to work in the health-care field in some capacity, and she has no idea if or when she will be able to realize that ambition.

'When you think of a Sleeping Beauty, you think of like a princess. And we're nothing like that when we're in that state.'—Kaitlyn Terrana

Her social life is also tenuous. Never knowing when she will have an episode meant not signing up for a class trip to Montreal, and she had to turn down a friend's invitation to go to Cuba early next year.

While she has a group of supportive friends, including a boyfriend, she says she has lost several friends because of her illness. She has even been bullied online by one former friend who accused her of faking KLS to get attention — a charge for which there is no evidence, Callen confirms.

"It's really hard for me," Kaitlyn says, fighting back tears . "I try so hard to persevere, but I just keep getting brought down by this."

Even so, she is trying to raise awareness of KLS and to raise money for research being conducted at Stanford University in California.

"I'm not doing this for myself. I'm doing this for the next batch of people who get diagnosed with KLS, so they know they're not the only ones out there with it," says Kaitlyn, who was contacted by a Hamilton man with the syndrome after her story ran in a local newspaper.

That article also mentioned that KLS has been dubbed "Sleeping Beauty" disease, a moniker some readers took umbrage with, given how it affects young people's lives.

"It doesn't bother me," Kaitlyn says of the name. "It's just the fact that it's not a pretty syndrome.

"When you think of a Sleeping Beauty, you think of like a princess. And we're nothing like that when we're in that state."