When Ontario teenager Kaitlyn Terrana is having one of her episodes, she can sleep for 20 hours a day, 10 days at a time.

That's because Terrana has Kleine-Levin Syndrome -- sometimes dubbed the "Sleeping Beauty" disorder -- that causes her to sleep for long chunks of time, CBC reported.

"In the beginning of her episodes, she starts off being very, very tired. 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," Terrana's mother, Kathy, told CBC. "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."

Kleine-Levin Syndrome is incredibly rare -- ABC News reported that only about 1,000 people have it in the entire world -- and it can also be hard to diagnose. In Terrana's case, CBC reported that a diagnosis for the condition didn't come until a year and a half after her first episode because there is no set test for the condition.

The condition is more common in boys than in girls -- with 70 percent of people who have the condition being male -- and the excessive sleep is often accompanied by symptoms of extreme food intake, an increased sex drive, hallucinations and feelings of being disoriented, according to the National Institute of Neurological Disorders and Stroke.

The Kleine Levin Syndrome Foundation reported that episodes of the condition usually appear during adolescence, and can go away and come back again in a cycle. An episode is described as such:

At the onset of an episode the patient becomes progressively drowsy and sleeps for most of the day and night (hypersomnolence), waking only to eat or go to the bathroom. When awake, the patient's whole demeanor is changed, often appearing "spacey" or childlike. When awake he experiences confusion, disorientation, complete lack of energy (lethargy), and lack of emotions (apathy).

There is no cure for the condition, but "watchful waiting" is generally advised, the National Institute of Neurological Disorders and Stroke reported. In some cases, drug treatments can actually make the condition worse.

Terrana is not the first teen to make headlines for Kleine-Levin Syndrome. Earlier this year, The Sun reported on the case of British teen Stacey Comerford, whose latest episode lasted two months.

"When she's in an episode, she might get up to go to the toilet or get a drink but she's not awake. I call it sleep mode," Comerford's mother, Bernie, told The Sun, adding that she feeds her when she's in this trance-like state. "When she wakes, she thinks it's the following day. She doesn't have any memory of it."

Also on HuffPost:

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  • Sleep Paralysis

    If you've ever drifted off to sleep or just woken up from sleep but were unable to move any part of your body -- spurring a sense that you are frozen in your bed -- you may have experienced sleep paralysis. Sleep paralysis is more common in the seconds to minutes when we're first waking up, whether in the morning or in the middle of the night, Gehrman said. When we are in REM sleep, our muscles are paralyzed so that we don't act out our dreams. But with sleep paralysis, a part of the brain wakes sooner than the rest, giving a sense of wakefulness and alertness -- even though the body's muscles are still paralyzed, Gehrman explained. However, <a href="http://www.stanford.edu/~dement/paralysis.html" target="_hplink">sleep paralysis isn't dangerous</a> despite the unsettling feeling experienced by people who have been through it, according to Stanford University. To decrease the number of sleep paralysis episodes you have, stress reduction, getting enough hours of sleep a night and making sure you have a good sleep schedule could help.

  • REM Sleep Behavior Disorder

    Opposite to sleep paralysis, REM sleep behavior disorder occurs when your brain is in REM sleep but your muscles are acting out your dreams, Gehrman explained. WebMD explains the <a href="http://www.webmd.com/sleep-disorders/guide/rem-sleep-behavior-disorder" target="_hplink">signs of the disorder</a>: <blockquote>Dream-enacting behaviors include talking, yelling, punching, kicking, sitting, jumping from bed, arm flailing, and grabbing. An acute form may occur during withdrawal from alcohol or sedative-hypnotic drugs.</blockquote> Stanford Sleep Disorders Clinic sleep specialist Tracy Kuo, Ph.D., told Everyday Health that this <a href="http://www.everydayhealth.com/sleep/other-disorders/REM-behavior-disorder.aspx" target="_hplink">disorder could potentially be violent</a>, especially if the person is kicking or punching his or her self or partner while sleeping. "Without treatment, it tends to get worse over time," she told Everyday Health. However, there are medications a person can take to help people relax their muscles when they sleep so that they <a href="http://www.everydayhealth.com/sleep/other-disorders/REM-behavior-disorder.aspx" target="_hplink">don't have any muscle activity</a> when they are in REM sleep, Everyday Health reported. REM Sleep Behavior Disorder has also been linked to <a href="http://www.webmd.com/sleep-disorders/guide/rem-sleep-behavior-disorder" target="_hplink">neurodegenerative diseases</a> like Parkinson's disease and multisystem atrophy, and seems to occur several years before these diseases, WebMD reported.

  • Sleep Walking And Talking

    Similarly to sleep paralysis, sleep-walking and sleep-talking occur when part of the brain is awake but the rest of it is asleep, Gehrman said. "With sleep-walking, people are mostly asleep but you're engaging in what are usually kind of basic routine behaviors," Gehrman said. "So typically, people sleep walk and go to the bathroom, or go down to the kitchen and get something to eat, but it's all usually very routine." Because sleep-walking and sleep-talking occur in non-REM sleep, since non-REM sleep only produces bland, boring dreams, whatever the person is saying or acting out is not related to what they may actually be dreaming about, he said. However, Gehrman said that there is not yet a clear answer as to why we say or act out the things we do when we are sleep-walking or sleep-talking. Sleep-walking isn't inherently dangerous, but if a child is prone to sleepwalking, Honaker recommends that parents take safety precautions by locking windows, putting safety latches on doors, etc., so that sleep-walking children don't accidentally hurt themselves.

  • Bedwetting

    Bedwetting, also known as enuresis, is defined as involuntary urination by a child who is older than age 5 or 6 (either in the day or night), according to the A.D.A.M. Medical Encyclopedia. Sarah Morsbach Honaker Ph.D., a pediatric sleep psychologist at the University of Louisville, told HuffPost that bedwetting is very common in children, and that most kids outgrow it as they get older, many times without any intervention. Honaker said a possible cause for bedwetting is maturational delay, meaning a child's body hasn't yet matured to maintain bladder control throughout the night. "You wouldn't expect a 2-year-old to be dry throughout the night," Honaker told HuffPost. "For some kids, this ability matures later than others." In addition, some kids may just have a lower arousal threshold, meaning that it takes more to rouse them from sleep if their bladder is full, she said. "Because enuresis is outgrown, there's a tendency in some cases for healthcare providers to make the decision not to treat it," Honaker said. "However, there has been research to suggest it impacts self esteem and can have social consequences." Because of that, she suggests that kids whose lives are strongly impacted by bedwetting to consider an intervention like a bedwetting alarm, which senses moisture and goes off so the child wakes up to go to the bathroom.

  • Night Terrors

    Night terrors, also known as sleep terrors, occur more often in children, who tend to outgrow them by adolescence, Honaker said. She also clarified that they are not the same thing as nightmares. "When a child has a sleep terror, they're asleep, so typically what will happen is they will be inconsolable, seem very upset, crying, screaming, and don't even seem to recognize the parent when the parent comes into contact with them," Honaker said. Sleep terrors can go on from 2 minutes to 20 minutes or longer, and they can be very scary for parents, she said, but parents should rest assured that sleep terrors are not at all harmful for the children. "They're asleep, so there's no lost sleep, and we don't see them feeling fatigue the next day," she said. "There's typically no recall, and that's a hallmark with a sleep terror." Honaker said that anywhere from 1 to 6 percent of children will experience a sleep terror, with the typical age of onset being between 4 and 12 years old. For parents, the best thing to do is <em>not</em> wake the child up -- "it can actually make the episode worse because the child doesn't see them as a parent," she said.

  • Teeth Grinding

    Teeth grinding, also known as bruxism, occurs when you <a href="http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002386/" target="_hplink">slide your teeth back and forth</a>, and can occur in both the day and night time, according to the A.D.A.M. Medical Encyclopedia. It can be annoying to sleep partners, and can even lead to joint pain or damage in the area. Teeth grinding is a result of any number of factors, including stress, misaligned teeth, ability to relax and sleeping habits, the A.D.A.M. Medical Encylopedia reported. Gehrman said that sometimes, lowering stress and anxiety can help to reduce teeth grinding at night. To manage teeth grinding -- though it isn't a cure -- people can go to their dentists to get a mouth guard to protect their teeth at night.

  • Exploding Head Syndrome

    Exploding head syndrome is definitely more unusual than some other sleep occurrences like sleep-walking or sleep-talking, Gehrman said. "From descriptions, it's this bizarre experience that it does feel like your head is exploding" because of a loud noise going off in the head, Gehrman said. However, he noted that it's not dangerous. The American Sleep Association <a href="http://www.sleepassociation.org/index.php?p=explodingheadsyndrome" target="_hplink">describes it as</a>: <blockquote> ... Similar to a bomb exploding, a gun going off, a clash of cymbals or any other form of loud, indecipherable noise that seems to originate from inside the head.</blockquote> Gehrman said that there is little research on the phenomenon, but it seems to be a very extreme variation of hypnic jerks -- those weird leg jerks that occur when you're first falling asleep. The American Sleep Association reported that people over age 50 and women are more likely to experience the phenomena, and that it's asso<a href="http://www.sleepassociation.org/index.php?p=explodingheadsyndrome" target="_hplink">ciated with high stress and fatigue</a>.

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