Top 10 Most Bizarre Sleep Disorders


Insomnia, sleep apnea, sleepwalking – you’re probably well aware of some of the most common sleep problems, but did you know there are over 100 official types of sleep disorders? Some of them are truly biologically bizarre (to say the least) and would be absolutely terrible to suffer through. You thought your nights struggling with insomnia were bad? Next time, thank your lucky stars you don’t have one of the following sleep disorders.

1. Kleine-Levin Syndrome

What’s the longest you’ve ever slept? 10 hours? 12 hours? Imagine if you needed to sleep 20 hours a day. Every day. Sound crazy? Not if you have Kleine-Levin Syndrome (KLS). Also known as Sleeping Beauty syndrome, KLS is a very rare disorder that (despite what the nickname implies) typically occurs in adolescent males. It strikes in episodes that last a few days or weeks, and then normal sleep behavior returns. Oftentimes, those who suffer from KLS have no recollection of the episode – a disturbing thought considering what can happen. According to the National Institute of Neurological Disorders and Stroke, KLS episodes can entail “excessive food intake, irritability, childishness, disorientation, hallucinations, and an abnormally uninhibited sex drive.”

2. Non-24-Hour Sleep-Wake Disorder

Most people have an internal, master clock that runs just a bit over 24 hours and is reset each day as the sun rises. For those with non-24-hour sleep-wake cycle – one of the rarest sleep disorders – their internal clock is not reset each day making their sleep-wake cycle ever-shifting and out of sync with the rest of the word. The disorder is most common among blind people since their bodies don’t register the day and night environmental cues.

Here’s how it’s explained on

For unknown reasons, most people's body clock runs a little longer than 24 hours, which means most people could have Non-24 to some degree. The difference is that for sighted people, environmental light cues signal the brain to reset the master body clock every day to 24 hours.

For people who are totally blind, the master body clock runs its natural course. This means that if your body clock runs on a 24.5-hour schedule, today you're 30 minutes behind and tomorrow your body clock will be an hour behind. The next day will be 90 minutes, and so on. Day by day, this time adds up until you're many hours behind, creating a rhythm that's out of sync with the typical day-night cycle. Eventually, your body operates as if night is day and day is night. While you could try to maintain your usual schedule, more often than not you have a hard time sleeping at night and then feel an overwhelming urge to sleep during the day. In time, you once again reach the point when your body clock is in sync with the typical day-night cycle. But then, just as quickly, it moves out of sync again.


3. Sudden Arrhythmic Death Syndrome

You’re probably very familiar with Sudden Infant Death Syndrome (SIDS) – when a baby dies unexpectedly in its sleep – but if you’re an adult or adolescent and the same thing occurs, it’s known as sudden arrhythmic death syndrome (SADS) – or sudden adult death syndrome or sudden unexpected/unexplained death syndrome (SUDS). Experts don’t yet know why, but it primarily occurs in otherwise healthy, young Asian males. (In the Philippines it’s known as bangungut – "to arise and moan," the Tagalog word for "nightmare.”) In the end, those who suffer from this fate may scream, moan, and froth at the mouth just before death occurs and it’s impossible to wake them up. The actual cause of death is heart failure, and research by Dr. Joseph Brugada found a possible genetic link – but why it occurs during sleep is still a mystery.

4. Sleep Paralysis

Have you ever woken from a dream only to find you can’t move a muscle? Then you’ve experienced sleep paralysis. Human sleep consists of cycles between rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. REM sleep is when brain activity increases significantly causing us to dream and, to keep the body from acting out our dreams, our bodies enter a state of paralysis. Still, over 30% of people experience waking during REM sleep while their body is still paralyzed – sleep paralysis (SP). It’s a common symptom of narcolepsy, but it’s also associated with psychiatric disorders, jet lag, student status, and even general sleep loss. Even worse than the freaky feeling of paralysis are the hallucinations that typically accompany it. According to one systematic review of the research, “unnatural involuntary movements (e.g., levitation), the presence of malevolent intruders in the bedroom, and physical/sexual assaults are common SP hallucination themes.” As terrifying as sleep paralysis can be, it’s virtually harmless and typically only lasts a few seconds to a few minutes. (Still, trying to get back to sleep after those terrifying moments will probably take a lot longer.)


REM Sleep

5. REM-Sleep Behavior Disorder

Quite the opposite of sleep paralysis, REM-Sleep behavior disorder causes people to act out their dreams - and the result can be embarrassing or even dangerous. The National Sleep Foundation explains it as follows:

For most people, dreaming is purely a "mental" activity: dreams occur in the mind while the body is at rest. But people who suffer from REM sleep behavior disorder (RBD) act out their dreams. They physically move limbs or even get up and engage in activities associated with waking. Some engage in sleep talking, shouting, screaming, hitting or punching. Some even fly out of bed while sleeping! RBD is usually noticed when it causes danger to the sleeping person, their bed partner, or others they encounter. Sometimes ill effects such as injury to self or bed partner sustained while asleep trigger a diagnosis of RBD. The good news is that RBD can usually be treated successfully.


6. Sleep-Related Eating Disorder (SRED)

There’s no harm in enjoying a midnight snack here and there, but nearly 5% of the population suffers from sleep-related eating disorder (SRED) that leads to compulsive, almost nightly, overnight indulging. Oftentimes, the person has no recollection of the event the following morning.

 According to the American Academy of Sleep Medicine, problems resulting from SRED include the following:

  • Eating strange forms or combinations of food, such as raw bacon, buttered cigarettes or coffee grounds
  • Eating or drinking toxic substances, such as cleaning solutions
  • Eating foods to which you are allergic
  • Sleep-related injury
  • High cholesterol
  • Excessive weight gain and obesity

 Some drug treatments have brought limited success, but there’s no known cure at present. Getting good sleep on a regular basis is strongly recommended since sleep deprivation makes the situation worse. (Technically speaking, sleep deprivation makes everything worse!)

7. Narcolepsy

Imagine having no control over when you fall asleep and spending most of your time awake feeling groggy and kind of stuck between wakefulness and sleep. That’s narcolepsy and it’s not just inconvenient, it can be downright humiliating and potentially dangerous. A study out of Stanford published in 2014 explains how it’s an autoimmune disease that makes your body kill the cells that produce the neurotransmitters in our brains that tell us when to sleep and when to wake up. And even though it affects roughly 250,000 people in the U.S., fewer than a quarter of those living with the disorder are correctly diagnosed. As Aleks Mencel writes in The Atlantic, “although four times more common than cystic fibrosis and nearly comparable in frequency to multiple sclerosis and Parkinson’s disease, narcolepsy is often mistaken for depression, epilepsy, bipolar disorder, learning impairments, or dismissed as laziness.”

8. Irregular Sleep-Wake Rhythm

People who suffer from irregular sleep-wake rhythms have no patterns of waking and sleeping hours. According to the American Academy of Sleep Medicine (AASM), “People with irregular sleep-wake rhythm may sleep off and on in a series of naps over a 24-hour period. The sleep pattern is broken up into pieces. This is similar to infants who may sleep for a few hours and then be awake for a few hours. If you add up all of the sleep times, the total sleep time may be normal for that age. During the day, it may seem like they are sleepy because they nap so much. During the night, it may seem like they have insomnia because they are awake for long periods of time during the night. Their sleep is broken up into pieces all day and all night.” The condition is incredibly rare – so rare, in fact, the AASM reports they have no idea how many people even have it.

9. Sleep Sex

As with sleepwalking or sleep-eating or sleep-talking, sexsomnia is acting out sexual behavior during sleep. It can be as minimal as making sexual noises or as serious as sexual assault – without intention or awareness. In some cases, it has led to legal proceedings over accusations of assault and rape and the defendants have been acquitted because they were technically sleeping at the time. According to Dr. Scott Williams and Dr. Christopher Lettieri, “It is non-rapid eye movement (NREM) parasomnia characterized by abnormal transitions between sleep and wake states. Most commonly, NREM parasomnias arise from slow-wave sleep (SWS). Because of a relative lack of cortical control, partial arousals from this deep state of sleep can lead to uninhibited manifestations of primal drives. In this way, sexsomnia is linked to other primal drives. For example, fear and anger may manifest as night terrors, whereas hunger and thirst manifest as nocturnal eating or drinking.” Thankfully, sexsomnia is a treatable sleep disorder.

10. Fatal Familial Insomnia

Insomnia is bad enough, but Fatal Familial Insomnia (FFI) is even worse than it sounds. This incredibly rare neurodegenerative brain disease is caused by a genetic mutation that impairs the part of the brain called the thalamus, which is in charge of our sleep-wake cycles. The thalamus is also involved in visual, auditory, and motor information; our sense of balance; our perception of pain; aspects of learning, memory, and language; and even our emotions and personalities. Since the thalamus is involved in so much of our functioning, FFI symptoms are widespread and far beyond simply insomnia – including progressive dementia, panic attacks, phobias, lack of appetite, having a body temperature which is too low or too high, high blood pressure, episodes of hyperventilation, and excessive sweating and salivation. In the end (typically 12-18 months after onset), FFI leads to the inability to walk, talk, and sleep – which is ultimately fatal. Thankfully, FFI is so rare it only affects one in 10 million people worldwide. Sadly, there’s currently no cure.


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