Narcolepsy

The word "narcolepsy" is derived from two Greek words: narkosis, meaning a benumbing, or sleep; and lepsis, meaning a sudden occurrence, a seizure. The medical term "narcolepsy" was coined by a French physician named Gelineau, who, in 1880, first described recurring episodes of unavoidable sleep - literally, of "sleep attacks." These episodes, Gelineau observed, came on as suddenly and as unpredictably as epileptic seizures, or convulsions. The patient would fall to the ground without warning, as would someone experiencing an epileptic seizure, but instead of the shaking of the limbs characteristic of epileptic seizure, sleep attacks involved no movement, just sleep. We now know that narcolepsy has nothing to do with epilepsy or true seizures, but is a disorder of sleep.

Before the First World War, narcolepsy was considered to be quite rare, but the encephalitis epidemics of 1917-1922 produced many cases and, as a result, the understanding of the disease grew. It was learned that there are four classical symptoms: excessive daytime sleepiness with attacks of irresistible sleep, drop attacks (or cataplexy), sleep paralysis, and sleep-related hallucinations. Many patients with narcolepsy do not have all these symptoms, but all narcoleptics have excessive daytime sleepiness - the tendency to fall asleep quickly when the environment is quiet or nonstimulating. 

Narcolepsy is fairly common, occurring about as frequently as multiple sclerosis - that is, one case in a thousand people. It is as common in men as in women and, though the exact cause is not known, there is a genetic predisposition; both narcolepsy and excessive sleepiness are much more common in relatives of patients with narcolepsy than in the general population. However, it is not simply an inherited disease; it can be caused by viral infections (such as those responsible for the encephalitis epidemics in 1917-22), head injuries, and (rarely) brain tumors. The disease commonly begins in adolescents and young adults, and the first symptom is usually excessive sleepiness. These young people fall asleep easily at any time during the day, which may be their only symptom until many years later. Curiously, in at least half of the cases, the symptoms begin after some disruption to sleep pattern, such as a change in the sleep-wake cycle, a traumatic emotional event (such as the death of a spouse or other tragedy), or some other stress that affects sleep. 

All patients with narcolepsy have excessive daytime somnolence, and most develop sleep attacks over the course of many years. Many narcoleptics develop drop attacks, sleep paralysis, and sleep-related hallucinations, though these symptoms may not all be present in every case. 

The symptoms of narcolepsy are so insidious that the disorder has the dubious distinction in medical circles of being the disease that takes the longest time interval between initial presentation and diagnosis. In one series it took an incredible ten years from the time patients first began to experience problems until the correct medical diagnosis was made.

Though the full mechanism of the disease of narcolepsy is not understood, an abnormality of REM sleep, the sleep of dreams, is thought to be the problem. Simply put, in narcolepsy inappropriate REM sleep intrudes into wakefulness, creating a desire for REM sleep so powerful that it cannot be denied. Remember, REM sleep is associated not only with vivid dreams, but also with paralysis of most of the major muscle groups of the body. This understanding of the inappropriate intrusion of REM sleep into wakefulness explains many of the clinical manifestations of the disease. It seems as though the brain of a patient with narcolepsy harbors an intense desire for REM sleep, lurking just beneath the surface and waiting for any opportunity to capture the function of the brain. 

In the sleep lab, patients with narcolepsy fall asleep very quickly, but instead of entering deep sleep the way normal subjects would, quickly enter REM sleep - often within only a few minutes. (Remember, normally the first REM sleep episode of the night occurs about ninety minutes after retiring.) It's as if narcoleptics must have REM sleep immediately. Over the course of the night, their amount of deep sleep is very much reduced (that's why they're chronically sleep deprived), their number of wakenings is greatly increased, and the total amount of REM sleep is also increased. This pattern of dominance of REM sleep, and the rapid onset of REM sleep, is a basis for diagnosing narcolepsy. 

During the day, many of the symptoms of narcolepsy occur because of sleep deprivation, which explains the chronic excessive daytime sleepiness that is the first sign of narcolepsy. In addition, people with narcolepsy have episodes when the REM sleep lying just beneath the surface of their alert state actually intrudes into wakefulness - pushes its way into control of the brain and forces them into the dream-like state of REM sleep.  

The drop attacks and sleep paralysis are thought to be related to an abnormality in REM sleep as well. Both these symptoms represent partial episodes of REM sleep, involving only the paralysis part of the sleep, not the dreams. It's as if the overpowering urge for REM sleep that is characteristic of narcoleptics has only partially taken over the brain and has achieved the paralysis of REM sleep without the sleep itself. 

Many patients with narcolepsy are excessively sleepy most of the time. They could easily drift off during movies, watching television, attending an after-dinner lecture, or in any other situation where the stimulation is minimal and sleep is, though not socially acceptable, not entirely inappropriate. 

Several times a day, narcoleptics endure the sudden onset of these irresistible urges. These attacks can occur anytime - while eating, working, driving - and often during activities that normally would preclude sleep. Though the sleep may last as long as an hour if the subject is in a comfortable position, the sleep attack usually lasts a much shorter time, only a few minutes perhaps, and the patient wakes up refreshed. There seems to be a refractory period after such a sleep, lasting one to two hours, during which time the narcoleptic will not have another sleep attack. With EEG monitoring, brain activity during these sleep attacks has been found to be characteristic of REM-type sleep.

Cataplexy 

The word "cataplexy" comes from the Greek kata, meaning down, and lepsis, meaning seizure, and is a symptom manifested by 70 to 90 percent of people with narcolepsy. 

Basically, drop attacks are sudden, unavoidable episodes of muscle paralysis, causing loss of postural tone. They are thought to be the result of REM sleep intruding on wakefulness, except they involve no sleep, just the paralysis that usually accompanies REM sleep. During these attacks, narcoleptics are fully awake and conscious, but feel their muscles loosen and give way suddenly. Sometimes this produces just the fleeting sensation of weakness, or perhaps a momentary partial loss of tone in one muscle group - a drooping of the head, a brief stutter, a buckling of the knees, or a weakening of the grasp of a hand. Sometimes, however, it produces a total powerlessness and collapse, a fall to the ground, perhaps leading to injury. The episodes can arise on their own, but the precipitating factor is often a strong emotional reaction such as anger or excitement. Even pleasant emotions such as joy or elation can cause the response; curiously, laughter is one of the commonest triggers. Because most cataplectic episodes are mild and short, they may appear to the observer (or even to the patient) to be only momentary lapses - perhaps categorized as clumsiness or being accident-prone. 

Sleep Paralysis 

Up to 50 percent of narcoleptics experience paralysis associated with sleep. The episodes occur just at sleep onset or on awakening. In either case, the subject is awake, and aware, but cannot move - can't talk, roll over, lift a hand, call out, even open up the eyelids to see. These episodes of total paralysis are short, lasting only one to four minutes, but are often associated with the last of the classic symptoms of narcolepsy - vivid hallucinations - that make the episodes of paralysis even more terrifying. Though they can be simple benign images, the hallucinations of narcolepsy are often wild and bizarre, nightmare-like events and, when they occur with sleep paralysis, usually produce extreme anxiety. Many patients find themselves bombarded with brightly colored images, loud noises, and frightening experiences - for example, the feeling of moving in space or floating above the bed - combined with a total inability to move. 

In African and Caribbean cultures, the word "zombie" is used to describe a corpse brought back to life by magical powers, and these narcoleptic hallucinations, when they occur with sleep paralysis, are among the most frightening of human experiences - with the horribly graphic bombardment of images, combined with the corpse-like inability to move or react at all. These "dreams" are all the more terrifying, as the subject is not even asleep but wide awake, and aware of the surroundings and of the unreality of the images. 

Sleep paralysis is not specific to narcolepsy; perfectly normal people can have occasional episodes of sleep paralysis, usually without hallucinations. 

With the combination of horrible and bizarre hallucinations, sleep and drop attacks, and paralysis on awakening, no wonder many patients with narcolepsy fear that they are mentally ill. 

Features of Narcolepsy 

Headache is a very common symptom in narcolepsy, as is memory loss, lethargy, and inability to concentrate, all resulting from chronic sleep deprivation. Automatic behavior, the performance of routine tasks by a person who is not consciously controlling the activity, is also common. A period of increased drowsiness usually precedes the automatic behavior, and it often occurs when a person is doing some repetitive, monotonous task. Though the person is able to complete the activity (often not completely correctly), he or she may actually have been asleep for part of the time and may not recall having done the activity when awakened afterward. Automatic behavior is not specific to narcolepsy, but it reinforces the narcoleptic's lack of self-trust and lack of dependability. Depression is a common consequence of the illness, as narcolepsy obviously interferes with one's ability to perform many normal human activities, such as holding a steady job, driving a car, operating machinery, attending meetings, and looking after young children. Many of these patients are considered to be slothful and lacking in interest or self-motivation. It is to be emphasized that narcolepsy is a disease and beyond the patient's control, and is a lifelong affliction.