Narcolepsy is a chronic disorder characterized by excessive daytime sleepiness. The reason for the sleep attacks is because the brain has reduced hypocretin cells, which transmit signals on wakefulness. This is attributed to by an autoimmune response, where the immune system mistakenly destroys the healthy hypocretin cells.
Are There Different Levels Of Narcolepsy?
There are two major levels of narcolepsy, which are differentiated by the presence of cataplexy. Narcolepsy with cataplexy is referred to as type 1 narcolepsy whereas narcolepsy without cataplexy is type 2 narcolepsy. People living with narcolepsy generally experience sudden sleep attacks, sleep paralysis, overwhelming tiredness and automatic behavior among other symptoms.
Type 1 Narcolepsy
Type 1 narcolepsy is narcolepsy with cataplexy. This is a level of narcolepsy where the individual experiences a sudden loss of muscle tone while a person is awake. As a result, the individual can experience weakness on the affected muscle and even lose muscle control. For example, buckling of knees and drooping of eyelids at worse, one may have a total body collapse and experience difficulties in speech and walking. The sudden loss of muscle tone, i.e. cataplexy, can be triggered by strong emotions including laughter, anger, stress and even fear. The onset of cataplexy can take weeks or years after excessive daytime sleepiness starts. Cataplexy attacks can last for a few seconds up to a few minutes and usually resolve immediately without any drastic effects. While this kind of narcolepsy can be frightening, the good thing is that one does not lose their consciousness. Additionally, patients with this level of narcolepsy have low levels of hypocretin.(1)
Type 2 Narcolepsy
Type 2 narcolepsy is different from type 1 narcolepsy in that patients do not exhibit symptoms of cataplexy. This means that individuals do not experience sudden brief muscle weakness, especially after an episode of strong emotions. It accounts for about 30% of narcolepsy cases. In addition to that, they have less severe symptoms compared to patients diagnosed with narcolepsy with cataplexy. Regardless of having normal levels of hormone hypocretin, individuals still experience excessive daytime sleepiness.
This is a minor type of narcolepsy which develops in individuals who have had an injury to the hypothalamus region. The hypothalamus is located deep in the region and helps in regulating sleep. So, if it has been damaged, a person may experience sleep problems which may include the excessive daytime sleep and inability to sleep well at night and requiring more than 10 hours of sleep per night. Other than that, patients with secondary narcolepsy may have neurological problems depending on the extent of injury. (1)
Determining The Level Of Narcolepsy
Clinically, the specific level of narcolepsy can be diagnosed by carrying out a lumbar puncture test to determine hypocretin levels in the cerebrospinal fluid (CSF). If levels are less than 110pg/mL, then an individual has type 1 narcolepsy, even without cataplexy. Another test that can be carried is the multiple sleep latency tests for excessive daytime sleepiness. The test involves a standard procedure over a 2-hour period with four or five nap opportunities. A patient with narcolepsy will fall asleep in less that 8 minutes with REM sleep occurring within 15 minutes, in at least two of the nap opportunities. Type 2 narcolepsy will be diagnosed if the patient has normal levels of hypocretin in CSF and if multiple sleep latency test results are positive. Individuals with type 2 narcolepsy can be diagnosed with type 1 thereafter if and only if they develop cataplexy and their hypocretin levels become abnormal. (2)
Generally speaking, individuals with either type of narcolepsy exhibit regular symptoms of narcolepsy. This is; excessive daytime sleepiness, fragmented night sleep, quick transition to REM sleep, hallucinations, sleep paralysis, and automatic behavior. The major differences between the two are cataplexy – the sudden loss of muscle tone. People with the different levels of narcolepsy also have different levels of hypocretin (orexin) levels. People with type 1 narcolepsy have a deficiency in hypocretin or low levels whereas those with type 2 have normal levels of narcolepsy.
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