Narcolepsy is one of the chronic illnesses of the nervous system that is majorly characterized by sleeping excessively during the day. This is called excessive daytime sleeping (EDS). This disease affects both sexes in a uniform manner and it normally starts during teenage years going into adulthood. Its prevalence rates have been compared to those of multiple sclerosis and Parkinson’s disease with the National Institute of Neurological Disorders and Strokes giving an estimate of one out of 2000 people being affected by the disease in the United States. These rates differ in different countries with Japan recording higher cases of 1 per 600 individuals while in Israel standing at 1 out of every 500,000 people.
Apart from the major symptom EDS, narcolepsy is also typified by cataplexy which is loss of muscle tone and sleep paralysis which incapacitates the patient’s ability to move or talk. Patients also suffer from hypnagogic hallucinations during which they experience distorted perceptions. Disturbed nocturnal sleep is also common among patients suffering from narcolepsy as well as engaging in automatic behavior whereby they carry out certain actions unconsciously. These symptoms may be present in varying degrees and combinations depending on the patient.
Despite the fact that almost 200,000 Americans have been estimated to suffer from the disease by the American Sleep Association, the figure of those who have been properly diagnosed falls short of 50,000. The disease often goes undiagnosed for long periods because physicians only relate it to patients who suffer from excessive daytime sleepiness without regarding other symptoms such as fatigue, or problems concerning concentration, memory and performance of tasks which are highly associated with narcolepsy. The other symptoms of the disease also occur much later after the onset of EDS which starts in puberty and continues into young adulthood, and may thus pass unrecognized.
There have been many researches carried out to find the cause of this nervous system disease-the latest findings attribute the EDS symptoms to the presence of structural and functional abnormalities of hypocretin neurons in the brains of narcolepsy patients. These abnormalities in the hypocretin systems interfere with the hypothalamus ability to transmit messages to other cells of the body. These abnormalities are manifested in the decreased levels of hypocretins in patients suffering from the disease.
The disease is also linked to a specific type of human leukocyte antigens (HLAs) which are genetically determined proteins on the surface of the white blood cells. The narcolepsy patients have been found to have high levels of the HLAs leading to the conclusion that the disease might be an autoimmune one. This implies that the narcolepsy patients are prone to losing nerve cells in their brains owing to destruction by their own immune system.
Debate on whether or not the disease is hereditary is still rife with researchers still investigating the possibility of this. There are inconsistencies as far as human patterns of the disease are concerned with relatives of narcolepsy patients being highly predisposed to the sleep-related abnormalities linked to the disease. In animals such as dogs, the disease is inherited in a predictable pattern and is attributed to mutation of a particular gene that normally produces a receptor for the hypocretin neurotransmitter in the brain.
