As written by Sascha Gallardo
Ben’s Friends Blog
You might have had some problems falling or staying asleep especially on nights when you have a lot on your mind. In fact, it is estimated that there are around 70 million people in the US that have chronic sleep disorders, according to the Centers for Disease Control and Prevention. 
But while many people are familiar with problems related to sleep in general, there are rare sleep disorders that many have not heard of.
Below are some of them.
Congenital Central Alveolar Hypoventilation Syndrome (CCHS)
CCHS is characterized mainly by hypoventilation (too slow or shallow breathing) during sleep, although some patients hypoventilate even when awake. This results in too much carbon dioxide and too little oxygen in the blood.
Aside from hypoventilation, patients may also suffer from blood pressure, heart rate, and temperature regulation problems among others.
This disorder is primarily caused by a mutation in the gene that is important for the development of the autonomic nervous system. CCHS may manifest during infancy (neonatal onset) or later in life.
Non-24-Hour (N24) Sleep-Wake Disorder
Many of our body functions, including sleeping, follow the circadian rhythm which goes through a 24-hour cycle. Most people with N24 Sleep-Wake Disorder, however, have longer than 24-hour circadian rhythm. This means that the schedule of their body functions is delayed every day which affects the time they sleep.
In some rare cases, patients have shorter than 24-hour circadian rhythm which causes them to sleep earlier everyday, instead. Such changes disrupt patients’ day-to-day activities as they suffer from fatigue and sleepiness during the day trying to keep up with the regular schedule.
Most patients suffering from this disorder are completely blind. This is because the morning light, which signals the brain that it is daytime by passing through the eyes, is not registered among blind individuals.
N24 Sleep-Wake Disorder, however, can also affect sighted individuals. In such cases, some of the possible causes include isolation or non-exposure to sunlight, abnormal production of melatonin, and insensitivity to light.
REM Sleep Behavior Disorder
When we sleep, we go through cycles of non-rapid eye movement (NREM) phase and rapid eye movement (REM) phase. The REM phase is when dreams occur. During this phase, parts of the body become paralyzed, the purpose of which is so that we don’t act out our dreams.
However, people with REM Sleep Behavior Disorder are able to move and vocalize during this phase, enabling them to act out their dreams, particularly the undesirable ones. Both the patients and their roommates are at risk of injury because of this.
Many of the patients with REM Sleep Behavior Disorder are male over 50 years of age, although it is not impossible to find women and children suffering from it. Other risk factors include use of antidepressants, alcohol, and drugs, as well as having narcolepsy and neurological disorders such as multiple system atrophy and Parkinson’s disease.
Fatal Familial Insomnia (FFI)
Fatal familial insomnia is a rare disorder that usually manifests in middle age, with mild difficulty sleeping at first, but worsens eventually. The patient’s mental and physical abilities deteriorate over time until the individual eventually dies.
As the name implies, FFI runs in families and is caused by a mutation of the PRNP gene. It is, however, also possible to have the mutant gene even without acquiring it from either parent although this is very rare.
Unfortunately, at present, there is still no cure for fatal familial insomnia.
Depending on the age, each person needs a specific amount of sleep daily. For instance, the American Academy of Sleep Medicine suggests that children aged 6-12 get 9 to 12 hours of sleep per 24 hours while teenagers aged 13-18 get 8 to 10 hours of sleep. 
However, individuals affected by Kleine-Levin syndrome can sleep as much as 20 hours per day during “episodes,” which can last for days or weeks. During this period, patients may also exhibit hyperphagia (excessive eating), irritability, hallucinations, and apathy, without recalling anything that transpired during this period once the episode subsides.
Most of the individuals affected by Kleine-Levin syndrome are adolescent males. At present, there is no specific treatment for this syndrome, although symptoms may improve after some years. Some patients even stop having episodes, but it’s possible to return much later in life.