As a rule, narcolepsy has a gradual onset between the ages of 15 and 35 years; in fully 90 percent of narcoleptics, the condition is established by age 25. Narcolepsy is usually the first symptom, less often cataplexy, and rarely sleep paralysis. The essential disorder is one of frequent attacks of irresistible sleepiness. Several times a day, usually after meals or while sitting in class or in other boring or sedentary situations, the affected person is assailed by an uncontrollable desire to sleep. The eyes close, the muscles relax, breathing deepens slightly, and by all appearances, the individual is dozing. A noise, a touch, or even the cessation of the lecturer’s voice is enough to awaken the patient. The periods of sleep rarely last longer than 15 min unless the patient is reclining, when he may continue to sleep for an hour or longer. At the conclusion of a nap, the patient feels somewhat refreshed. It should be emphasized that there are many narcoleptics who tend to be pervasively drowsy throughout the day. What distinguishes the typical narcoleptic sleep attacks from commonplace postprandial drowsiness and napping is the frequent occurrence of the former (two to six times every day as a rule), their irresistibility, and their occurrence in unusual situations, as while standing, eating, or carrying on a conversation. Blurring of vision, diplopia, and ptosis may attend the drowsiness and may bring the patient first to an ophthalmologist.
In addition to episodes of outright sleep, narcoleptics, like other very drowsy persons, may experience episodes of automatic behavior and amnesia. Initially the patient feels drowsy and may recall attempts to fight off the drowsiness, but gradually he loses track of events. The patient may continue to perform routine tasks automatically but does not respond appropriately to a new demand or answer complex questions. Often there is a sudden burst of words, without meaning or relevance to what was just said. Such an outburst may terminate the attack, for which there is complete or nearly complete amnesia. In many respects, the attacks resemble episodes of nocturnal sleepwalking. Such attacks of automatic behavior and amnesia are common, occurring in more than half of a large series of patients with narcolepsy-cataplexy (Guilleminault and Dement, 1978). Affected patients are frequently involved in driving accidents, even more frequently than epileptics.
Nocturnal sleep is often disrupted and reduced in amount. The number of hours in a 24-h day spent in sleep by the narcoleptic is not greater than that of a normal individual. Narcoleptics have an increased incidence of sleep apnea and periodic leg and body movements, but not of somnambulism.
Approximately 70 percent of narcoleptics first seeking help will report having some form of cataplexy, and about half of the remainder will develop cataplexy later in life. Cataplexy refers to a sudden loss of muscle tone brought on by strong emotion—that is, circumstances in which hearty laughter or, more rarely, excitement, surprise, anger, or intense athletic activity cause the patient’s head to fall forward, the jaw to drop, the knees to buckle, even with sinking to the ground—all with perfect preservation of consciousness. Cataplectic attacks occur without provocation in perhaps 5 percent of cases. The attacks last only a few seconds or a minute or two and are of variable frequency and intensity. In most of our patients, they have appeared at intervals of a few days or weeks. Exceptionally, there are many attacks daily and even status cataplecticus, in which the atonia lasts for hours. This is more likely to happen at the beginning of the illness or upon discontinuing tricyclic medication.
Most attacks of cataplexy are partial (e.g., only a dropping of the jaw or “weakening of the knees”). Wilson found that the tendon reflexes were abolished during the attack. Pupillary reflexes are absent in some cases.
Infrequently, cataplexy precedes the advent of sleep attacks, but usually it follows them, sometimes by many years. Sleep paralysis and hypnagogic hallucinations together are stated to occur in about half the patients.