The Sleepy Child
Narcolepsy and Other Causes of Sleepiness
For the two years preceding his first visit to me, Brendan napped between forty and sixty minutes every afternoon. He usually went to bed after dinner, at about 7:00 P.M., and slept until 6:30 A.M. That may not seem unusual, but Brendan was ten years old. Sometimes he also fell asleep in school for ten or fifteen minutes, although he could usually fight off the sleepiness until he got home. He was in the fourth grade when I saw him, and he was beginning to have both social and academic problems. His teacher was concerned and thought he should see a counselor.
Jacqueline, eighteen, was also unusually sleepy for her age. She slept ten hours a night and usually took at least two twenty-minute naps during the day. Sometimes she would abruptly become so sleepy that it was almost impossible for her to stay awake, even when she wasn’t sitting still. A year earlier, she had had a car accident—fortunately, a minor one—after falling asleep at the wheel. Since that time she had driven little and never alone. She quit college after her freshman year because she could not stay awake in class or complete her assignments. The excessive sleepiness had begun when she was fifteen, and by the time I saw her she had noticed two new symptoms. First, occasionally, just as she was about to fall asleep at night, she found herself unable to move at all, except to breathe and move her eyes; the paralysis continued for several minutes or until she fell asleep or someone touched her or talked to her. Second, when she laughed very hard, and sometimes when she felt angry, she became physically weak: she would have trouble holding her head up, or her knees would start to buckle, sometimes causing her to fall down. Both of these symptoms were frightening, and the episodes of weakness were often embarrassing; Jacqueline was reluctant to talk about them.
Both of these youngsters had a disorder called narcolepsy, whose main symptom is excessive sleepiness. Narcoleptic children usually develop other symptoms eventually as well: like Jacqueline, they may have sudden attacks of weakness during the day (cataplexy) and experience temporary paralysis and occasional hallucinations while falling asleep or on waking (sleep paralysis and hypnagogic hallucinations, respectively). In fact, cataplectic episodes such as Jacqueline’s are a principal feature of this disorder. Brendan had not yet developed cataplexy, but he almost certainly would later on.
Although uncommon, narcolepsy is hardly rare. In the United States, about one in two thousand children will develop it—about half as many as will develop multiple sclerosis and five times as many as have cystic fibrosis. It occurs with equal frequency in boys and girls. If you attend a baseball game with forty thousand other fans, about twenty of them are already suffering from narcolepsy, or soon will be.
Narcolepsy usually does not appear before children are in their midteens, although, as in Brendan’s case, it can happen. Both Brendan and Jacqueline had had symptoms for several years before their conditions were diagnosed and they began treatment. Most narcoleptic patients go eight to ten years or longer before being diagnosed, not because earlier diagnosis is impossible but because the symptoms are often misunderstood or unrecognized.
Not all overly sleepy children have narcolepsy. Sleepiness is also a symptom of other sleep disorders, various medical problems, and depression. Abnormally sleepy children are often thought to be simply “lazy” or “sluggish,” a potential error that physicians can make as easily as families. But sleepiness is a serious complaint that should not be dismissed lightly. If your child seems sleepier than he should be, be sure to investigate further. If he seems very sleepy day after day without an obvious cause, see that he gets medical attention.
Is Your Child Abnormally Sleepy?
If you suspect that your child might have narcolepsy or any of the other problems discussed in this chapter, the first question to ask is whether he really is excessively sleepy. Extreme cases are obvious, but the milder the sleepiness is, the harder it is to make this judgment. Approximate normal amounts of sleep for children of various ages are listed in Figure 1,. If your child sleeps up to two hours longer than the average for his age but seems fine during the day, then he probably just needs more sleep than most, which is usually nothing to worry about. If he averages more sleep than that, however, or seems tired during the day despite getting all the sleep he wants at night, there may be some cause for concern. For instance, an eight-year-old who sleeps fifteen hours every night should be seen by a physician, even if he is wide awake and cheerful during the day—he may simply be a long sleeper, but a need for that much sleep can be a sign of trouble. Napping that persists into elementary school age is another sign of excessive sleepiness. Napping ordinarily decreases significantly by age four and it is uncommon by age five. Any child of age six or older who still takes regular naps or who starts napping regularly again, however short the naps, may well be abnormally sleepy.
It is harder to decide if your child is too sleepy if he looks tired but does not actually fall asleep, or perhaps falls asleep only when riding in the car. He may be irritable; he may yawn and seem low on energy. He may have difficulty sitting still and keeping his attention focused. (Parents, teachers, and doctors often misdiagnose these symptoms of excessive sleepiness in a young child as hyperactivity, a learning disability, or simple laziness.) Although there are ways of quantifying sleepiness in the laboratory, mild excessive sleepiness is often difficult to recognize with certainty by observation alone. So if your child has any of these symptoms, it would be wise for you to be suspicious.
Causes of Sleepiness Other Than Narcolepsy
Some causes of sleepiness are easy to identify; others are not. If you judge that your child is sleepier than he should be, the next questions to ask are whether he is getting a sufficient amount of sleep and whether the quality of the sleep is good. Without laboratory study it may be impossible to be certain about the quality, but you can make some important observations on your own.
First, consider the amount of sleep your child gets. Keep track of his sleep patterns for several weeks. Pay close attention on weekends and holidays to determine how much sleep he gets when he does not have to wake up for school or day care. For example, if your ten-year-old is hard to wake for school after nine hours of sleep and remains sleepy during the day, but on the weekend he wakes spontaneously after eleven hours and stays alert all day, then nine hours is simply not enough sleep for him. Teenagers are especially likely to get too little sleep, because they often like to stay up late and because they are particularly prone to phase shifts (see Chapter 10). If your teenager goes to sleep at 2:00 A.M., wakes at 6:00 A.M. for school, and naps every afternoon, it should be clear why he needs those naps. Some teenagers also seem to have a very long sleep requirement. Teenagers can binge on sleep on the weekends, especially if they do not get enough sleep during the week. When they get the chance, they can sleep fifteen hours at night and possibly nap during the day too. But they should not do so seven days a week; if your teenager does, you should be concerned.
Second, try to determine whether your child is sleeping well once he goes to bed. This determination is quite difficult to make outside the laboratory, but if your child is very restless or seems to wake often during the night, even if only for short periods, or if he snores every night, especially if the snoring is loud and he gasps and struggles to breathe, his sleepiness could be coming from poor quality of sleep as well as from inadequate or insufficiently deep sleep.
If the problem is insufficient sleep, you may be able to correct it yourself. But if your child is sleepy despite appearing to get enough good sleep, or if his sleep appears to be of poor quality, or if you’re just not sure of the cause, you should seek medical consultation.
Many medications cause daytime sleepiness, among them antihistamines used to treat allergies and many of the medications used to treat seizures. Illness of any sort can leave a child feeling fatigued and sleepy. Viral infections, especially mononucleosis and hepatitis, and any illness that produces a high fever are especially likely to cause fatigue. But the sleepiness should not last for months: it should go away soon after the fever does, or after no more than several weeks in the case of a slower-resolving viral infection. Children with anemia, hypothyroidism, and certain other chronic conditions tend to be tired, but truly excessive sleepiness is uncommon in these conditions. High and low blood sugar levels rarely cause significant sleepiness. Serious illnesses, including cancer, can certainly make a child appear run-down and, to some extent, cause him to sleep more.
If your child is never wide awake, you should be greatly concerned. If he sleeps long hours at night, naps repeatedly during the day, and is still never fully alert between naps, he certainly needs medical attention. If this behavior is not the temporary consequence of an acute illness or a recently started medication, he must be evaluated for serious medical and psychological conditions as well as for basic sleep disorders such as narcolepsy and sleep apnea.
Treating Simpler Causes of Sleepiness
If your child is mildly sleepy due to inadequate sleep at night, you need to help him increase his sleep time according to the methods outlined in other chapters of this book. In these cases the main problem is the insufficient sleep, and the daytime sleepiness is only a consequence.
If it seems that your child simply has a long sleep requirement, your family may have to make a few adjustments to allow for it. That may not always be easy or practicable. An adolescent who requires eleven hours of sleep and needs to get up at 6:30 A.M. for school would have to go to sleep at 7:30 P.M. to get enough sleep every night. You will have to arrive at a compromise. Perhaps your child can have a relatively early bedtime on weekdays, maybe 9:00 or 9:30, and make up the missing sleep by sleeping late on the weekend or taking naps. (However, the amount of morning and daytime sleep must not be so great that he becomes unable to fall asleep early enough at night.) Although such a remedy is less than ideal, it may be workable and it can be enough to produce an improvement. If your child has been going to bed at 11:30 P.M. until now, the extra two hours of sleep each night could make a big difference.
If your child’s sleepiness results from illness, medication, or a medical condition, work with your doctor to find ways of alleviating his symptoms. A change in medication or in dosage regimens may be helpful, for example.
Evaluation at a Sleep Disorders Center
If neither inadequate sleep nor known medical factors seem to explain your child’s sleepiness, then a full evaluation is crucial. It may reveal an undiagnosed medical disorder, an emotional problem such as depression, or a primary sleep disorder—that is, one involving basic sleep mechanisms.
If at all possible, your child’s sleep should be evaluated in a sleep laboratory. Not all medical centers have the facilities to carry out sleep studies, especially in children. However, sleep disorder centers are growing in number, and even if the one nearest you mainly sees adults, its staff can probably test your child or at least refer you elsewhere.
Two kinds of sleep study are useful in evaluating a sleepy child. In the first, a sleep study or polysomnogram (PSG), the child is monitored during the night. This study aims to answer questions including:
· How long does it take the child to fall asleep? (A truly sleepy child is unlikely to lie awake for a long time, even in the laboratory.)
· Does the child get a normal amount of sleep, too much, or too little?
· Does he go through all the normal sleep stages, and do they last the expected lengths of time? In particular, are the deepest phases of non-REM sleep, Stages III and IV, present and sufficiently long? (These stages contribute the most to feeling well rested.)
· Are sleep stages well maintained, or is sleep broken by frequent arousals? (Fragmented sleep, even if it adds up to a normal amount, can cause sleepiness.)
· Does the child show the normal pattern of cycling from one stage to the next?
· Does the beginning of REM sleep occur at the expected time, or does it start too early? (In narcolepsy, and to a lesser extent in depression, REM tends to appear very soon after the start of sleep. Children with narcolepsy often enter REM sleep within ten minutes of falling asleep at night, and even faster during naps.)
· Does the child have sleep apnea, and if so, how severe is it?
· Are there any brain wave (EEG) abnormalities, especially patterns that suggest epileptic seizures or tumors?
A second study, the Multiple Sleep Latency Test (MSLT), is carried out on the day after the initial sleep study, if possible. It measures a child’s actual degree of sleepiness and his tendency to enter the REM state rapidly. The child is monitored, as he was at night, but this time not continuously. Instead, every two hours he is allowed to lie down in a dark, quiet room and given twenty minutes to fall asleep. If the child does fall asleep, he is allowed to sleep for fifteen minutes. This procedure is repeated four or five times at two-hour intervals. (Special modifications of this routine may be required for young children, when some napping is still normal.)
Most children fall asleep only occasionally during this test, and it will usually take them more than twelve minutes to fall asleep, averaged over all the trials. Abnormally sleepy children will fall asleep in most of the trials and in only five to ten minutes. Narcoleptic children usually fall asleep within two or three minutes in all or almost all of the trials, and at least two of the naps will include extremely rapid transitions into REM sleep, called sleep-onset REM periods or REM onsets.
If the results of a sleep study and MSLT are normal, then it is unlikely that your child is abnormally sleepy. That doesn’t mean he isn’t physically tired in the daytime. (You could be tired after a game of tennis or running around the block, yet not feel at all sleepy.) His fatigue may still have a medical or an emotional basis.
If testing confirms that your child is very sleepy, but he does not appear to have narcolepsy (that is, if he falls asleep rapidly or deeply in the MSLT but never enters REM), and his sleep both at night and during the day is normal, then, once medical factors are eliminated, psychological causes and another sleep disorder (similar to narcolepsy but without the REM abnormalities) must be considered.
While adults suffering from depression usually sleep poorly, youngsters, especially adolescents, sometimes react to depression quite differently, withdrawing into their inner world of sleep as a way of escaping from problems that seem too difficult to face. How they do that is unknown, but the sleep is genuine and long lasting. They may sleep deeply at night and have repeated naps during the day. They may even spend most of the day in bed. If your child is exhibiting this behavior, don’t wait for the problem to pass on its own. Seek medical and psychological help.
Finally, the child who is sleepy, but for whom a specific medical or psychological cause cannot be identified, is said to have idiopathic hypersomnolence—that is, we know he is sleepy, but we don’t know why. Idiopathic hypersomnolence may reflect several different disorders that happen to have the same symptoms, but because the pattern of difficulties is often quite similar from one child to the next, it is thought that most people with this problem probably have the same disorder, or perhaps one of a few closely related disorders. These problems tend to run in families. For instance, it’s fairly common for one parent and several children in a family to have the symptoms, often almost from birth. Children with idiopathic hypersomnolence tend to be long sleepers and long or frequent nappers, but otherwise they are normal. Often there is no need to treat them until they start school, when their sleepiness starts to interfere with learning and socialization.
Although insufficient sleep is the most common cause of daytime sleepiness, narcolepsy, idiopathic hypersomnolence, and sleep apnea are the three main sleep disorders that cause it. You will recall that in sleep apnea the problem is an inability to breathe normally while asleep, which in turn causes the sleep disruption (see Chapter 17). Although children with sleep apnea are often sleepy during the day, the signs of that sleepiness are often subtle. In narcolepsy and idiopathic hypersomnolence, the daytime sleepiness is more evident. In these disorders, the brain systems responsible for controlling sleep are directly affected.
Narcolepsy usually appears starting in adolescence or early adulthood, but it can begin in the primary-school grades and occasionally even earlier. About 50 percent of narcoleptics show symptoms by age sixteen. The symptom of excessive sleepiness, once present, never leaves. If symptoms start in early childhood, they may worsen as the child goes through adolescence. Patterns of sleepiness sometimes change temporarily during pregnancy, either improving or worsening. Otherwise, after adolescence these patterns tend to remain fairly constant for years. The symptoms of sleep paralysis, hypnagogic hallucinations, and cataplexy, on the other hand, are more variable and tend to wax and wane in frequency and severity over time.
The condition has no known cure, though the sleepiness may eventually decrease as the narcoleptic adult reaches middle age, and some of the other symptoms may even disappear. All of the symptoms can be treated with naps and medication. Often treatment is very successful, but both the severity of the disease and the response to therapy vary widely.
Narcolepsy is often confused with epilepsy. It is in fact a completely different disorder, although some of its symptoms occasionally resemble certain forms of epileptic seizures. In narcolepsy, sleep systems turn on inappropriately during the day, and they don’t always work as they should at night. Although both REM and non-REM sleep are affected, most often it is the REM system that becomes active at the wrong time, accounting for most of the symptoms.
Sleep Disturbances in Narcolepsy
Despite the common misconception, most narcoleptic patients are not truly “hypersomniac”—that is, the amount of sleep they get each twenty-four-hour period is actually normal or nearly normal, and their sleep is not unusually deep. Often their nighttime sleep is broken by many brief wakings and a few longer ones, just as their daytime waking is broken by naps. Sleep is thus distributed across the twenty-four-hour day rather than consolidated into a single block at night. (When the disorder first appears in childhood, the pattern is often different. Affected children often go to bed early—possibly right after school, even skipping dinner—and sleep through until the next morning, getting eleven to sixteen hours of sleep. By stretching out the night in this way, they seem to be able to avoid sleeping during the rest of the daytime hours. The quality of narcoleptic children’s sleep is generally good, unlike in adults. When narcoleptic children do nap, they may sleep for two or three hours. By contrast, adult narcoleptics generally take brief, refreshing naps of about twenty minutes.)
As mentioned above, the other main characteristics of sleep in narcoleptics is that REM sleep frequently occurs immediately upon falling asleep, or at most within ten minutes. In normal infants older than three months, REM does not ordinarily occur until a full cycle of non-REM sleep has completed. Older children may even have two non-REM cycles before their first REM period. Outside of narcolepsy, REM onsets are seen only under a few conditions: during withdrawal from a medication that decreases REM sleep (which leads to a “REM rebound”); on returning to sleep in the morning soon after waking; when going to sleep at the wrong time, such as after a large and abrupt time-zone change or when on a very irregular sleep schedule; and, possibly, after a period of sleep deprivation.
Because not all of a narcoleptic’s sleep periods begin with REM, a study of one nap or one night’s sleep may not be sufficient to diagnose the disorder. But the repeated naps of the MSLT can be decisive: if a child takes only a few minutes to fall asleep during the tests, and if he goes right into REM sleep in at least two of the naps, we can usually confirm the diagnosis of narcolepsy.
Partial Activation of the REM System
Sometimes narcoleptics have episodes in which REM systems are functioning but REM sleep is not fully established. As described below, this unusual phenomenon can happen at bedtime, on waking, or during the day, and it accounts for the other symptoms of narcolepsy: cataplexy, hypnagogic hallucinations, and sleep paralysis. In these conditions, certain features of the REM state, namely dreaming or paralysis or both, seem to be activated while the patient is still fully awake or only partly asleep.
The Major Symptoms of Narcolepsy
Sleepiness and cataplexy are the hallmarks of the narcolepsy syndrome. If your child has both of them, then a diagnosis of narcolepsy is fairly certain.
The Sleepiness of Narcolepsy
Narcoleptic children are continually sleepy. They will fall asleep quickly whenever there is nothing happening to keep them awake. However, when they are up and about and not in monotonous or tedious settings, most narcoleptics can stay awake. Most of them feel very sleepy from time to time during the day—and these periods of marked sleepiness can come on fairly rapidly—but with a strong enough motivation to stay awake and an ability to move around, narcoleptics can fight off sleep, at least for a while. If they do fall asleep, they can be wakened.
Narcoleptics do not really fall asleep suddenly and without warning, as is often believed. We all feel irresistibly sleepy on occasion, but narcoleptics feel that way every day, and their desire to sleep is much more overwhelming. To give you an idea of how a narcoleptic person feels, imagine watching a dull program on television in a very warm room after a big dinner. Your eyelids feel heavy; you know that you will not be able to stay awake unless you get up and go for a walk. It feels good just to let yourself fall asleep. Trying to fight off sleep is difficult and unpleasant. If you do fall asleep, you will probably wake after a short nap feeling much better. The overwhelming sleepiness will be gone.
What narcoleptics experience is no different, except that the urge to sleep can come on at any time during the day, though most commonly and most intensely in settings where anyone might find it hard to stay awake. Without physical activity, narcoleptics find it almost impossible to fight off sleep. Even if they do manage to stay awake, they feel groggy and their ability to concentrate is greatly diminished.
Typically an adolescent or adult narcoleptic’s naps are short—sometimes only a few minutes, occasionally up to an hour, but rarely much longer. And the naps often do seem to be considerably refreshing. At school, for example, a narcoleptic adolescent can often resume productive work if he is allowed to nap for twenty minutes. If he has to fight off sleep instead, he may be unable to concentrate for hours, finding it impossible to remain still, listen quietly, and stay awake at the same time. He must move about and talk, or else he will fall asleep. Either way, he will probably wind up in trouble with the teacher. (Remember, younger children with narcolepsy may sleep long hours at night and not seem particularly sleepy during the day. Any naps they do take tend to be long; if the children are wakened after twenty or thirty minutes—which may be difficult—they will probably seem groggy rather than refreshed.)
Cataplexy is a sudden muscle weakness, or even temporary total paralysis, triggered by strong emotion. This dramatic symptom is very disconcerting and even dangerous to the narcoleptic, although it may strike an uninformed observer as funny. Laughter and anger are typical triggers, but any strong emotion or excitement can initiate a cataplectic event. Cataplectic adults often learn to control their emotions rigidly, avoiding all expressions of laughter, anger, or excitement. Children in the family, however, may delight in provoking them to laughter just to watch them fall over at the dinner table.
Cataplectic attacks vary from person to person in frequency, severity, and length. Your child’s cataplectic weakness may be very mild—his knees may buckle briefly, his jaw may sag, or he may have a moment’s difficulty holding his head up—or it may be so severe that he falls to the ground, unable to move any muscles except those that control breathing and eye movements. Most cataplectic attacks last between a few seconds and one minute. Less often, attacks last several minutes, and on rare occasions they can last up to half an hour. An episode that continues for several minutes may lead into a period of sleep. Most untreated narcoleptics with cataplexy have between one and four cataplectic attacks each day. Some patients have them less often; others experience cataplexy many times each day with very little provocation.
Severe, frequent cataplexy is crippling if untreated. Even infrequent attacks can be very dangerous if the weakness is pronounced. Although serious injuries are uncommon, an unfortunately timed attack can cause a person to drop a pot of boiling water or fall down the stairs. Outside the home, the dangers can be even greater: a child might fall down in the street if he is startled by an approaching vehicle, and an adolescent or adult can have a cataplectic attack while driving a car.
Like the attacks of sleepiness in narcolepsy, cataplexy is entirely distinct from epilepsy, despite some superficial similarities. Although it can be tempting for observers to assume the weakness is imagined or “hysterical,” especially when it is precipitated by unusual circumstances, for example, when the sufferer is frightened or sexually aroused, it is very real. Cataplexy is a true weakness, identical to the paralysis that occurs during normal REM sleep (see Chapter 2). The system controlling REM paralysis seemingly turns on suddenly and inappropriately during the day instead of confining itself to periods of REM sleep. Why cataplexy can be triggered by emotion is not yet known.
The age at which cataplexy first appears in narcoleptics varies greatly. Cataplexy and sleepiness may or may not begin at the same time; even several years can elapse between the onsets of the two symptoms. Most often, sleepiness appears first. Cataplexy usually follows within five years, but much longer delays are seen occasionally. It is rare for cataplexy to appear in a child of five or younger. By early adolescence it is seen more often, but roughly 85 percent of narcoleptics do not develop the symptom until after the age of fifteen.
Cataplexy can be difficult to recognize. Many children have trouble describing the weakness they feel during mild episodes. Even if you see your child drop to the floor when laughing hard, you are unlikely to be alarmed. Many normal children fall to the ground or flop down onto the table when they are laughing hard and feeling silly. But you should be concerned if your child seems frightened by his weakness at these times, has difficulty getting back up once he has stopped laughing, or experiences a similar weakness when he is angry or startled. Cataplexy in older children is usually easier to recognize, at least in part because they can describe their own perceptions of the weakness better than younger children can.
The Minor Symptoms of Narcolepsy
The two other important symptoms often present in narcoleptic patients are sleep paralysis and hypnagogic hallucinations. These symptoms are not required for a narcolepsy diagnosis, since they aren’t present in all patients with narcolepsy and they are present in some people without the disorder. Like cataplexy, they reflect a partial activation of the REM system.
Children who have sleep paralysis find themselves alert but unable to move. This phenomenon is similar to cataplexy, but it does not occur during full waking. It happens during the transition to or from sleep, most frequently just when a narcoleptic child is about to go to sleep, less often just as he wakes. As in cataplexy, sleep paralysis involves the paralysis of REM sleep occurring an inappropriate time, in this case just before or just after actual sleep and dreaming. Most episodes last only a few minutes. They end either spontaneously or when broken by some outside stimulation, typically touch or sound. Generally, sleep paralysis occurs only a few times a month. In rare patients it happens almost nightly.
Sleep paralysis can begin at any point in the development of narcolepsy. About two-thirds of narcoleptic patients have at least occasional episodes of sleep paralysis, and about half of all patients have repeated episodes; one out of four develops the symptom by age sixteen. Not surprisingly, sleep paralysis can be frightening to children, especially the first time it occurs.
Occasionally, just as a narcoleptic child is drifting off to sleep, he may see or hear something imaginary that seems very real. This is called a hypnagogic hallucination. (The senses of smell, taste, and touch are less commonly involved in the hallucinatory experience.) These visual or auditory hallucinations can be pleasant or scary. A child might see only moving colored blobs or hear meaningless noises, but more often, the images are better formed. The child may visualize scenes that appear to him to be believable or bizarre. He may hear music or voices. He may see burglars, strangely shaped or oddly colored animals, or threatening monsters. The theme of intrusion and threat is common, and the imagery can be quite realistic. Whether a child recognizes these visions or sounds as unreal may depend on his age and how close to sleep he is. The child may also hallucinate that he is doing something, perhaps running away or trying to fight back an attack. If he has sleep paralysis at the same time as a hypnagogic hallucination and is thus truly unable to move at all, he may understandably find the experience particularly frightening.
Hypnagogic hallucinations occur just before falling asleep. They reflect a partial activation of the REM system in which a dream has begun while sleep and (generally) paralysis have not. (Similar phenomena, so-called hypnopompic hallucinations, may occur on waking in both normal children and narcoleptics and reflect the continued activity of part of the dream system for a few minutes after waking.) Although about half of all narcoleptics eventually develop hypnagogic hallucinations, only 15 percent have them by age sixteen.
Since hypnagogic hallucinations can be scary, a child who often experiences them may resist going to bed. Young children may have difficulty describing these experiences, while older children are often afraid to talk about them for fear of being thought crazy, especially if the images they experience are very bizarre. (You should not think, however, that all children complaining of “seeing” monsters at night are having hypnagogic hallucinations; most are not. Monsters that are the products of a normal, vivid, waking imagination are far more common than those produced by an abnormal activation of the dream system.)
The occurrence of hypnagogic hallucinations may simply be a consequence of the fact that the transition from wakefulness to sleep takes time—as wakefulness only gradually gives way to sleep. Normally this transition is directly into non-REM sleep, and if we are at all aware that non-REM is starting, we will only notice that we are getting very sleepy or that our thoughts are starting to wander and we are starting to daydream. But in the narcoleptic, the transition is from waking directly into REM sleep, and if it is gradual enough, the person may be aware that true dreaming has started before he is completely asleep. Not only that, but the dream imagery present is often quite intense. (The intensity of the dream imagery may well be part of the abnormality of the REM sleep system in narcolepsy; the same abnormality probably also accounts for the fact that narcoleptics have more frightening nightmares than most people.) The narcoleptic’s awareness of the unreal nature of these hallucinations depends on how early in the transition to sleep the dream actually began.
Many narcoleptic patients find that their best course is not to fight off the hallucinations but just to let full sleep overtake them. That probably doesn’t end the dream, but conscious awareness gradually slips away.
The Importance of an Early Diagnosis
Although in narcolepsy any of the four characteristic symptoms can be the first to appear, in nine out of ten affected children the initial problem is sleepiness. Cataplexy usually follows within a few years. Hypnagogic hallucinations and sleep paralysis, if they appear, may begin at any point.
Sometimes symptoms start abruptly, possibly following an important incident in the child’s life. Emotional trauma, for example, is occasionally associated with the onset of sleepiness. In these cases, the initial diagnosis may incorrectly identify the sleepiness as a psychological problem, and the true cause of the symptoms may not be recognized for a long time. Other times, when the sleepiness starts gradually, the parents and child might blame it on insufficient sleep or increased school demands.
Cataplexy, on the other hand, is unmistakably abnormal in clear-cut cases, and once it has become noticeable it is usually brought to medical attention. Narcolepsy is the most likely diagnosis and it will probably at least be suspected, although sometimes the symptom is misinterpreted as a form of epilepsy or hysteria. If the cataplexy is less pronounced, if the child is not yet showing excessive sleepiness, or if the doctor doesn’t know enough about narcolepsy, the disorder can go undiagnosed for years.
Whether the initial symptom is sleepiness or cataplexy, the personal cost of a delay in diagnosis and treatment can be enormous. A child’s academic performance and self-esteem may suffer tremendously as he goes through school with an undiagnosed handicap. In perhaps one-third of all narcoleptic patients, sleepiness begins early enough to interfere with performance in elementary school or high school. Later on, it can cause people to unnecessarily change their plans for further education or even a career. In older children it can be the cause of significant social problems. People may assume the child is lazy or has “psychological problems.” Undiagnosed narcoleptics sometime enter psychotherapy in an attempt to treat the symptoms, an effort which will not be successful because the real problem is not being treated. (A therapist can, however, help a patient learn to cope with the symptoms of narcolepsy once it has been properly diagnosed.)
For these reasons, it is important to recognize narcoleptic symptoms as early as possible. Many parents don’t seek help for their child immediately unless the symptoms are dramatic, which they often are not. Even when sleepiness is so excessive that it is impossible to ignore, parents may well assume that it will pass. (And sometimes it does, for example, if it was the result of a low-grade viral infection or some emotional struggle rather than narcolepsy.) Prominent sleepiness that persists more than a week and mild sleepiness that lasts over a month or two should definitely be evaluated.
Although we cannot predict which children will eventually develop narcolepsy, at least not yet, there is some evidence that these youngsters’ sleep habits may be unusual even before major symptoms emerge. Retrospective studies on adult narcoleptics suggest that many of them continued napping into grade school. Over 10 percent of them were also misdiagnosed as hyperactive in childhood and treated with stimulants because they could not sit still and pay attention. (This may be a case of the right drug for the wrong reason, since narcolepsy and hyperactivity respond well to some of the same medications; see below). You should be especially suspicious if your child seems overactive yet still naps inappropriately.
Sleep Paralysis, Hypnagogic Hallucinations, and Cataplexy Without Narcolepsy
Although the symptoms of sleep paralysis and hypnagogic hallucinations are characteristic of narcolepsy, both can occur independently as well, not as part of the narcolepsy syndrome. In fact, many people without sleep disorders experience one or the other from time to time.
When they are not accompanied by excessive sleepiness or cataplexy, sleep paralysis and hypnagogic hallucinations present no cause for alarm. Independent sleep paralysis in children occurs most often as the child is waking, as might be expected, since children (like adults) commonly wake directly from REM sleep, whereas sleep-onset REM periods usually occur only in narcoleptics. Independent hypnagogic hallucinations occur as a child is falling asleep, and they can be quite intense and even frightening. However, they happen only occasionally.
Independent cataplexy is much rarer than independent sleep paralysis or hypnagogic hallucinations. Some researchers believe that cataplexy is always a sign of narcolepsy and that it only appears to be independent when the symptom of sleepiness is not yet apparent. This theory is plausible, since cataplexy does sometimes precede the onset of sleepiness by many years. In any case, if your child experiences cataplexy, he should see a doctor. Cataplexy can be dangerous in and of itself, and symptoms resembling cataplexy can also be caused by other disorders.
The Cause of Narcolepsy
In recent years, research into the cause of narcolepsy has made outstanding progress. Some facts are now certain. But research continues advancing rapidly, with new theories constantly emerging or being disproved. What we know so far is that a previously unknown neurotransmitter (a chemical that nerve cells release to stimulate other nerve cells) called hypocretin or orexin has been found in the lateral hypothalamus, a region of the brain known to be important in the control of certain basic body functions such as appetite. Dogs with a certain inherited form of narcolepsy have a defect in the nerve cell sites that are supposed to respond to this chemical, and mice that lack the gene necessary to produce it exhibit a similar syndrome. While most humans with narcolepsy do not show either of these genetic defects, they do have markedly reduced levels of hypocretin, and some evidence points to a loss of the nerve cells that produce it. It may be that these cells are normal at birth and become damaged later in life, which would explain why narcolepsy does not usually start until the second or third decade of life and why it does not grow worse over time. (Symptoms may actually become milder over many years, but it is not known whether this is because damaged cells regain some function or whether another mechanism is involved.)
Most narcolepsy is sporadic, which is to say that the condition is not a straightforward inherited trait. Furthermore, there is only a 1 in 4 chance that the identical twin of a narcoleptic patient will also develop narcolepsy, and no more than a 1 in 50 chance that the child of a narcoleptic parent will. If narcolepsy were simply a genetic disease, then if one identical twin developed narcolepsy, the other twin always would too. But if genetics had nothing to do with it, the risk to the twin would be only about 1 in 2,000, the same as the risk to the population in general. The implication is that some trait is inherited that increases the risk of narcolepsy but is not by itself enough to cause the disorder.
In that light, another discovery is extremely important: nearly 90 percent of all narcoleptic patients with both sleepiness and cataplexy have a characteristic gene in the so-called HLA region of one chromosome. Since genes in this region are known to be important to the immune system, which recognizes viruses and bacteria as foreign and attacks them, and since most diseases associated with HLA genes are autoimmune in nature—that is, the body attacks its own cells—this finding suggests that narcolepsy might be an autoimmune disease as well. The trigger may be a virus that, due to the defective gene, the immune system cannot distinguish from the brain’s normal hypocretin-producing cells: the response to the infection damages or destroys these cells along with the virus. Although studies have found some support for this idea, to date all attempts to confirm this hypothesis have failed.
In a small number of families narcolepsy is clearly genetic, passed consistently from generation to generation. However, in these families the disorder is slightly atypical: often it starts earlier, takes a milder form, and has no association with a specific HLA gene. There is evidence suggesting that at least some of these families have genetic defects similar to those found in affected dogs or mice, although the defect may not be the same in all families affected.
These developments are exciting, because they suggest that soon, for the first time, we may be able to start designing treatments aimed at correcting a specific chemical abnormality rather than simply treating the resulting symptoms.
The Treatment of Narcolepsy
The majority of people with narcolepsy can expect that, with treatment, most of their symptoms will be brought under control. Usually, the patient can achieve a normal life. Though children who develop narcolepsy will always have the disorder, it need not interfere seriously with their schooling, work, or social life. These children should not plan to become airplane pilots or long-haul truck drivers, but there are few other limitations on their life choices.
We treat narcolepsy with medication, judicious napping, appropriate schedules that allow for sufficient sleep, education, and common sense. Treatment must be supervised by a doctor. And we handle the different symptoms of narcolepsy in a variety of different ways.
The sleepiness of narcolepsy can be lessened with medication and a carefully maintained schedule. A short regular nap after lunch or at other times can help a child stay alert and use less medication during the day. In primary school, that can often be managed without upsetting the child’s overall schedule; for example, the child may be able to nap at the nurse’s station. In addition, when we are treating a young narcoleptic child at our clinic, we (and the family) contact the child’s school and discuss the disorder with his teachers and counselors. If a nap is necessary, we set up a place and time that prevent embarrassment. Teachers must understand that they should never punish or ridicule the child for falling asleep in class, and they should help educate the child’s classmates about the disorder and discourage them from teasing.
Adolescents often have a harder time fitting naps into their schedule, especially naps that occur on a regular and predictable basis. It may mean missing classes, and leaving class to nap may make an adolescent feel different from his peers and uncomfortable. (Although adult narcoleptics can often manage a short nap during their lunch hour every day, teenage patients usually cannot fit a nap into the typical half-hour lunch period.) However, a child of any age can take a short nap after school before beginning his homework, at least if after-school activities and jobs do not interfere.
While parents can usually control the schedule of a child in primary school, adolescents can present more of a problem: some try to keep up the (possibly unreasonable) schedule of their peers, even to the extent of denying that they have narcolepsy, and alcohol can become a factor, since it causes drowsiness. However, most adolescents are willing to acknowledge the disorder and accept limitations on their late-evening activities and alcohol consumption.
A proper medication regimen should keep a child needing as few naps as possible during school and allow him to participate in after-school activities and do his homework. There are a few kinds of drugs available for this purpose. Often one preparation works better for a given child than another. Stimulants such as methylphenidate (Ritalin, Concerta) and the amphetamines (Dexedrine, Adderall) have proven useful for many children. These drugs do have potential for abuse, but that is not a major worry in childhood, when parents control the dosage; significant side effects (like loss of appetite and weight loss, abdominal pain, nervousness, and tics) can be a concern, though, particularly at high doses. Pemoline (Cylert), a drug with wakefulness-enhancing properties similar to those of the stimulants, also works well, but it is rarely used anymore because it has been associated with very uncommon but serious liver toxicity. In fact, it is no longer available everywhere.
Modafinil (Provigil) is a newer drug that seems to help narcoleptic patients stay awake without many of the problems often seen with stimulants. Modafinil seems to affect only a very small area of the brain (possibly directly affecting the hypocretin/orexin system that has been implicated in the cause of narcolepsy), without causing the more widespread brain stimulation seen with other wakefulness-promoting agents. Patients on modafinil don’t “crash” as the medication wears off or get a buzz from an effective dose, and there seems to be little or no potential for abuse. At this writing, modafinil has not yet been formally approved for use in children younger than age sixteen (but initial studies on children have been completed, and there is the full expectation that it will be approved for children very soon). Even before governmental approval, your doctor can legally prescribe it if seems appropriate. Today, most children with narcolepsy, like their adult counterparts, are started on modafinil as the initial treatment.
Another drug even more recently approved is sodium oxybate (Xyrem). Although approved specifically for the treatment of cataplexy, studies have shown it to also improve the quality of a narcoleptic’s sleep at night and possibly to decrease sleepiness during the day. Its mechanism of action is uncertain, and to date there is very little experience of its use in children.
Depending upon how severe the symptoms are and which drug is being used, a child may need medicine once or several times a day (or, in the case of sodium oxybate, at bedtime and once during the night). He should be followed closely by a doctor knowledgeable about narcolepsy, and dosage decisions should be reviewed frequently.
If the child is old enough to drive, the physician should be involved in decisions about that as well. Generally, a teenager should be allowed to drive only if his sleepiness—and cataplexy, as described below—are satisfactorily controlled and the child is felt to be mature and reliable. The child should never drive late at night or alone for long periods.
Once sleepiness is properly controlled, the child often shows dramatic changes. There are usually major improvements at school, at home, and in the child’s social life. With Brendan, we were able to significantly reduce his daytime sleepiness by allowing him to nap after school (also during school on occasion) and putting him on a daily dose of methylphenidate. He felt much better about himself, and his schoolwork improved considerably. He continued to do well when I later switched him to modafinil. He no longer slept overly long hours at night; instead, he spent the time after dinner with his family or doing homework. Jacqueline, too, responded to medication (pemoline at first, switching to methylphenidate when the risks of pemoline became known, and then to modafinil when it became available), and she was able to finish college.
Cataplexy, Hypnagogic Hallucinations, and Sleep Paralysis
Cataplexy, hypnagogic hallucinations, and sleep paralysis usually respond well to medications ordinarily used in the treatment of depression, namely the tricyclics and the selective serotonin reuptake inhibitors (SSRIs). Sodium oxybate given at night, although not an antidepressant, also decreases cataplexy significantly, perhaps because of its known effect of improving sleep and decreasing REM onsets (though how it does that is unknown).
The symptoms of hypnagogic hallucinations and sleep paralysis, if they are present at all, don’t always need to be treated, especially if they are mild and occasional. They are annoying and somewhat frightening, but they are not dangerous, and once children understand why these symptoms occur they often learn to accept them. If a child’s cataplexy is very mild and episodes are rare, treatment may also be postponed. But if the cataplexy is dangerous, embarrassing, or frightening, it should be treated.
Jacqueline’s cataplexy was moderately severe, and besides, it was important to her that she be able to laugh freely in public without fear of embarrassment or of injuring herself. So her medication program included treatment for cataplexy, and both that symptom and her sleep paralysis were easily controlled. If Brendan required similar treatment, it probably would not be for several years, but he and his family knew what to look for and would understand the symptoms if and when they appeared.
A number of drugs to treat the symptoms of narcolepsy are in varying stages of development, including some that mimic the effects of the deficient hypocretin molecule itself. It is hoped that such research will lead not only to better treatment of symptoms but also to treatments directed at the cause of the disease itself, and thus effectively to a cure.