Narcolepsy (EDS) is a chronic disorder of the central nervous system characterized by the brain’s inability to control sleep-wake cycles. At various times throughout the day, people with narcolepsy experience irresistible and sudden bouts of sleep, which can last from a few seconds to several minutes. Cataplexy is a related, sudden loss of muscle tone that leads to feelings of weakness and a loss of voluntary muscle control. Attacks can occur at any time during the waking period, with individuals usually experiencing their first episodes several weeks or months after the onset of excessive daytime sleepiness (EDS)
In narcolepsy, sleep episodes can occur at any time and without warning. People may unwillingly fall asleep while at work or at school, when having a conversation, playing a game, eating a meal or most dangerously when driving an automobile or operating other types of machinery. Contrary to popular belief, people with narcolepsy do not spend a substantially greater proportion of their time asleep than do normal sleepers. In addition to daytime drowsiness and uncontrollable sleep episodes, most individuals also experience poor sleep quality that can involve frequent awakenings during nighttime sleep. For these reasons, narcolepsy is considered to be a disorder involving the loss of control of the normal boundaries between the sleeping and waking states.
While the cause in rare cases is a genetic defect, it appears most often to be the result of a loss of the brain cells that produce a chemical in the brain called hypocretin, which is responsible for sleep. The reason for such cell loss is unknown but appears to be autoimmune in nature. Narcolepsy cannot yet be cured, and when cataplexy is present, the loss of hypocretin appears to be permanent. In most patients, narcolepsy can be managed with medication. Modafini and sodium oxybate are two drugs approved for the treatment of narcolepsy.