This is a sleep disorder characterized by the daytime drowsiness, sleep paralysis and hallucinations. This condition can present difficulties with staying awake regardless of circumstances affecting the daily routine. Sometimes, it can also be accompanied by episodes of cataplexy which is the partial or total loss of muscle control triggered by a strong emotion such as laughter. The symptoms can begin in childhood or adolescence and several of the affected individuals experience the condition for several years before they are diagnosed.
Causes
The exact cause of this disorder is not known but most of the affected individuals have a decreased level of a neurochemical called hypocretin that regulates the wakefulness and the rapid eye movement (REM) sleep. In the normal sleep cycle, the REM occurs around 60 to 90 after entering sleep and the muscles become limp during this stage to prevent individuals from acting out their dreams. Among people with this condition, they can enter the REM sleep within 15 minutes after sleep and the dream activity of REM sleep can also occur.
Symptoms
This is a lifelong condition that can sometimes improve with time but never completely disappears. The common symptoms are the excessive daytime sleepiness, sleep paralysis s, cataplexy and hallucinations. The excessive daytime sleepiness can be experienced regardless of the amount of nighttime sleep they have. The sleep attack is the overwhelming sense of sleepiness that happens quickly. Cataplexy is the sudden onset of muscle tone loss when the individual is awake causing muscle weakness and loss of muscle control that can be triggered by strong emotions such as laughter, anger or stress. Cataplexy can vary in severity with the mild form presenting minor weakness of the limited muscles such as drooping of the eyelids to the severe episodes when the individual may be unable to move, talk or keep their eyes open. Sleep paralysis is the temporary inability of the affected individual to move or talk when falling asleep or waking up which can last for seconds or minutes.
Diagnosis
The diagnosis is based on the sleep patterns and includes tests to rule out other possible causes such as sleep apnoea, depression and epilepsy. Individuals will also be asked to record in their journal the duration of sleep and the symptoms. The two specific tests done for the sleep disorders include polysomnogram that is an overnight recording of REM sleep occurrence, the brain and muscle activity along with the eye movements. Multiple sleep latency test measures the time it takes to fall asleep during the day. In addition, the level of hypocretin may also be measured by taking a sample of the cerebrospinal fluid in a process called spinal tap.
Treatment
There is no cure for this disorder but treatment can help manage the symptoms. The mild cases can be managed with a change of sleeping habits although the severe case may require medications. Some of the medications used to treat the symptoms include a type of stimulants and sodium oxybate to reduce the daytime sleepiness.
References
http://www.nhs.uk/Conditions/Narcolepsy/Pages/Treatment.aspx
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Narcolepsy-Fact-Sheet
https://sleepfoundation.org/sleep-disorders-problems/narcolepsy-and-sleep
http://www.mayoclinic.org/diseases-conditions/narcolepsy/basics/definition/con-20027429
