In the classic fairytale by the Brothers Grimm, a beautiful princess named Aurora pricks her finger on a spindle and succumbs to a century-long sleep — a spell that could be broken only by a kiss from a handsome prince.

Many of us grew up with this bedtime story, but you might be unfamiliar with its real-life equivalent. In fact, for people who have been diagnosed with a rare neurological condition called Kleine-Levin Syndrome (KLS), excessive slumber is anything but fiction.

Not Just Fiction: About Sleeping Beauty Syndrome

Also known as Sleeping Beauty Syndrome, KLS is a condition marked by long periods of excessive sleep. It typically affects teenagers, but children and adults can have it, too.

People with Sleeping Beauty Syndrome can sleep up to 20 hours a day; the condition occurs in episodes or cycles that can last days, weeks, or even months. Because of this, many people with KLS are unable to work, attend school, or care for themselves during episodes.

Sleeping Beauty Syndrome Signs and Symptoms

Symptoms of KLS include:

  • Sleeping most of the day and night
  • Abrupt onset, sometimes accompanied by flu-like symptoms
  • Spaciness or childishness
  • Lethargy
  • Excessive food intake or food cravings while awake
  • Irritability
  • Depressed mood
  • Disorientation
  • Hallucinations
  • Progressive drowsiness

KLS is most common in adolescent boys: An estimated 70 percent of people with this syndrome are male. People with KLS usually act completely normal between episodes.

A Challenging Concern: Treating Sleeping Beauty Syndrome

There’s still much we don’t know about KLS, but it appears to be related to a malfunction of the hypothalamus and thalamus, the parts of the brain that control appetite and sleep.

There are also no diagnostic tests to screen for KLS. If you suspect that you or a loved one might have this condition, your physician will likely ask you about your symptoms and rule out other causes of sleepiness, which can include depression and, in teenage girls, premenstrual syndrome.

Likewise, no specific treatments exist for KLS. Although stimulant medications may help combat sleepiness, they can increase irritability. Some physicians prescribe drugs such as lithium and carbamazepine to counteract symptoms, but these medications aren’t always effective and can have side effects.

RELATED: Sleep Paralysis Causes and Prevention

Most physicians recommend watchful waiting without treating KLS. The frequency and severity of KLS episodes tend to ebb over time.

Learn more by visiting the UPMC Neurology Services website.