It is a sleep disorder that causes daytime sleep, a disorder in the nervous system that disrupts the brain’s ability to control sleep-wake cycles, and a sleep disorder during the night where intermittent sleep is disrupted.
Narcolepsy is a disease that is not very common, but it affects 1 in 2000 people, often not being diagnosed correctly and receiving appropriate treatment from the beginning.
The age between 10 and 20 years is considered the main age for the onset of narcolepsy, and it is difficult to differentiate it for some because of the similarity between sleep due to lack of sleep at night and narcolepsy. Usually, the teacher complains about the child sleeping in class or low grades for the student due to his lack of attention to the lesson. The disease usually comes gradually, and the disease progresses with time, the disease stages are more difficult.
The first reason for narcolepsy and cataplexy is the lack of hypocretin, a substance that stimulates wakefulness and regulates sleep. Many vital factors may affect the level of hypocretin and its instability , including:-
1- Autoimmune diseases: Recent research has proven a relationship between these diseases and cataplexy, as the body makes antibodies that fight hypocretin-producing cells in the brain.
2- Family history: It has been proven that 10% of patients with cataplexy and narcolepsy have a family history of disease.
3- brain injuries
Despite adequate sleep during the night and due to a chronic nervous disorder, the disease occurs, and its symptoms appear where sleeping two hours after waking up:-
A- Excessive sleep during the day
Where sleeping in classrooms for children, sleeping during work hours for adults, or sleeping while driving, which causes traffic accidents (fig 1) .
It is a loss of muscle control, especially after an emotional excitement, and the muscles relax, including the muscles of the legs and jaw muscles
Which comes suddenly, even with adequate sleep at night, and extends from a few seconds to minutes, and usually occurs several times a day in the absence of appropriate treatment for the disease.
C- sleep paralysis
It is a state of losing the ability to move when getting up from sleep and may last for seconds
Other symptoms including:
Depression and social isolation
Troubled sleep, headache, hallucinations.
Fig 1: narcolepsy during class time in schools.
How to diagnose?
The diagnosis is made by a specialized doctor because the disease is rare, and other diseases that are similar in symptoms such as epilepsy and sleep are initially excluded due to insufficient sleep at night and the lack of thyroid gland production, through various medical tests.
Then the tests for narcolepsy are performed, which include the Epworth Sleepiness Scale (ESS), Polysomnography (PSG), the Multiple Sleep Latency Test (MSLT), and finally the hypocretin measurement, which determines the type of narcolepsy, whether type I or II.
There are two types of narcolepsy:-
1- Type I narcolepsy with cataplexy is characterized by low levels of hypocretin
2- Type II narcolepsy without cataplexy and characterized by controlled levels of hypocretin 
Two methods are used in treatment, behavioral therapy and pharmacotherapy:
by getting enough sleep at night and afternoon naps, as it reduces sleepiness episodes throughout the day, and treats any other sleep disorder to raise the quality of sleep at night.
Of the drugs used, Modafinil, which has shown success in treating moderate and simple cases, and its side effects are less common, unlike Methylphenidate, which is stronger, but its side effects are more common.
Venlafaxine is an antidepressant suitable for use in narcolepsy and cataplexy 
Sodium oxybate may be used to improve the loss of muscle control and aid sleep at night 
T. E. Scammell, Narcolepsy. New England Journal of Medicine, 373(27), 2654-2662. (2015).