After seeing one of the anime, known to one of the characters in the anime had the disease.
Actually this is arguably not a disease.
Only a rare disorder known by all people at first.
Then lets check !~

Narcolepsy, a sleep disorder where the sufferer attack is very difficult to maintain a conscious state.
Most of the time he was sleepy.
Conversely in the evening, many people with narcolepsy who complain can not sleep.
(In particular, there appears to be a strong relationship between individuals with this disorder with certain genetic conditions).

There are four classic symptoms (classic tetrad) in narcolepsy:
1. Excessive sleepiness (EDS)
Excessive sleepiness during the day is a common symptom of sleep disorders.
But if this sleepiness occurs in people who do not suffer from OSA (Obstructive Sleep Apnea) or PLMS (Periodic Limb Movements)

2. Cataplexy (cataplexy)
On the issue of falling asleep suddenly, some cases of narcolepsy accompanied by cataplexy, a loss of muscle control cause someone to faint.
This condition is triggered by a surge of emotion, be it sadness or joy.
(Usually the more positive emotions than negative emotions trigger cataplexy)

3. Sleep paralysis
Sleep paralysis is a condition in which the sufferer paralyzed can not move his body at all.
Source : Click !~

4. Hypnagogic
Is hallucinations that often arise when people just want to sleep.
However, what actually happens is that through dream consciousness waking consciousness, so that it appears as a hallucination.
(This typically occurs during the transition from conscious to sleep (hypnagogic) or from sleep to realize (hypnopompic.)


Some people think that narcolepsy is probably a type of autoimmune disease or multiple sclerosis .

Autoimmune disease, which is caused by an immune system reaction to the normal component of the body, the immune system considers normal component body as a foreign substance and creates antibodies to fight it. 
Multiple sclerosis, a disease that attacks the central nervous system in a chronic, unpredictable, and even progressive. The disease attacks and destroys brain tissue and spinal cord.
But some people still can not explain with certainty about these symptoms! ~