Editor's note: This is part five of a seven-part series on sleep disorders

A child sitting in the principal's office suddenly falls asleep. He is not being rude or disrespectful, and he didn't stay up all night watching movies or doing homework. He has narcolepsy. Narcolepsy affects approximately 200,000 men, women and children in the United States alone, according to the National Institute of Sleep Disorders. However, these statistics may be too low, as many who suffer from narcolepsy are not getting diagnosed and are not being treated -- especially the children.

What is Narcolepsy?
The Taber's Cyclopedic Medical Dictionary defines narcolepsy as "a chronic ailment consisting of recurrent attacks of drowsiness and sudden onset of sleep that are uncontrollable, irresistible and happen in unusual places and under unusual circumstances."

Narcoleptic children are not children who need more sleep and they are not children who require more sleep. Narcoleptic children cannot control when and where they fall asleep and may do so at any time during the day or night. According to Dr. Stephen Sheldon, director of the sleep medicine center at Children's Memorial Hospital in Chicago, Ill., discovering that a child has narcolepsy can be quite difficult. "One of the reasons for misdiagnosed and undiagnosed children with narcolepsy is the lack of widespread knowledge that sleep related problems present with many symptoms often diagnosed as other things," says Sheldon. "We don't know how many children out there have it and are not either not being diagnosed or are being treated for something else and never have a proper diagnosis. We don't know what the true denominator is."

Recognizing Narcolepsy
There are four "classic" signs and symptoms that indicate the presence of narcolepsy. Evidence of one, all or a combination of these four should be cause for concern, further evaluation and treatment. The symptoms include: excessive sleepiness during the day, cataplexy, sleep paralysis and hypnogogic hallucinations.

According to Sheldon, the first symptom -- excessive daytime sleepiness -- is the most significant of the four but should not be confused with a child who is need of sleep or who is sleep deprived. "Narcoleptic children tend not to have hypersomnia -- sleeping for long lengths of time," says Sheldon. "They just fall asleep uncontrollably. They don't know that they're sleepy yet they are very sleepy and sleep sneaks up on them at times when they don't expect that they would fall asleep -- like talking on the telephone; at the dinner table; during a conversation; at a party; whenever they sit still; driving in a car. They don't realize they are sleepy then all of the sudden they are asleep. This is referred to as 'excessive sleepiness during the day.'"

"My father was narcoleptic," says Kristina Powers, a mother of two from Petersburg, Va. "I would be talking to him and he would fall asleep -- out of no where. He would fall asleep when talking on the phone, when taking a shower -- any where at any time. He didn't drive because he never knew when it was going to happen."

Cataplexy is the second of the tetrad of symptoms. During normal sleep, the brain paralyzes the muscles of the body with the exception of the eyes and the diaphragm, resulting in a "floppy-rag-doll" like state, similar to when a father carries a young, sleeping child to bed. This cataplexy is a normal occurrence during sleep. However, for a narcoleptic child, this normal occurrence happens at abnormal times.

"In children with narcolepsy, the 'floppy-rag-doll' behavior can occur at any time during the day when they're awake -- not when they're sleeping," says Sheldon. "Narcoleptic children often exhibit symptoms of fainting. The problem is, nobody bothers to ask the child if they were awake after they fainted. If a child is experiencing cataplexy, they are aware of everything that is going on and will be able to offer details as to what was being said, who said it and what happened, but they can't move. This symptom is often precipitated by emotion. Laughter is probably the most common so if they laugh, they fall, become clumsy or weak or feel as if they have to sit down as a result of their muscles being paralyzed."

The third symptom is sleep paralysis, which is similar to cataplexy but occurs upon awakening. In narcoleptic sleep paralysis, the brain paralyzes the body at the time when the child wakes up. The brain wakes, but the muscles are still paralyzed and the child can't move or open his/her eyes. "I want to underline, bold face and italicize the word 'can't,'" says Sheldon. "The child can't -- not won't -- get up. This is not the child who complains, moans and groans that they don't want to get out of bed in the morning. It's the child who wakes up frightened because they couldn't open up their eyes or they couldn't move. It is scary to wake up and not be able to move."

The fourth symptom is termed "hypnogogic hallucinations." Our normal dreams are called hypnopompic hallucinations -- they occur upon awakening and can be remembered and described. Hypnogogic hallucinations are those that occur just as a person drifts off to sleep. According to Sheldon, there tends to be some universal hypnogogic hallucinations that many people experience such as a dream of falling that results in the person being startled awake. Children with narcolepsy have these types of dreams -- hypnogogic hallucinations -- but the dreams do not end, as they do not startle awake.

"Most commonly in children, the dreams usually involve the sleeping environment," says Sheldon. "Due to being so frightened at the beginning of the sleep period, children may tell their parents that there is someone who keeps walking in their room or that a monster walked into their closet. To the children, these dreams seem real, as they do not react by waking up when scared. The child then consistently has nocturnal fears and will complaining about seeing things, hearing things or that someone is calling their name at the beginning of their sleep period."

In addition to these symptoms, family inheritance is a factor in the presence of narcolepsy in children. However, there are families that are not aware of the family's trait of narcolepsy. "Narcolepsy is a genetic disorder," says Sheldon. "It is passed on genetically so people become genetically narcoleptic at the time of conception. We have many child patients who have narcolepsy -- and we can prove it -- and their parents have absolutely no symptoms but have the genetics for it. They don't know that they have it; they never knew that they had it and until we diagnosed their child they had no clue there was even any evidence of it."

According to Sheldon, any one of the symptoms in and of itself is not diagnostic of narcolepsy. It is only when a medical or family history combines itself with these symptoms that the presence of narcolepsy is suspected. "You have to have the combination of symptoms and often it is difficult in a child to make a clear-cut diagnosis," says Sheldon. "Unless you have a family history or the child has a cataplexic attack in front of your eyes, the diagnosis may go incomplete until they are teenagers. That's the reason why it's said that narcolepsy onsets in adolescence and young adulthood -- because that's when you can diagnosis it. But that doesn't mean necessarily that's when it begins."

Read about the onset and diagnosis of Narcolepsy in Part Two.