Narcolepsy is a neurological disorder of the sleep/wake and REM/non-REM systems. It is as common as MS, though the rate of diagnosis is only 25%. It can be very disabling, especially when untreated.

Narcolepsy is often mistaken for depression, chronic fatigue syndrome or simply not identified, as the symptoms are not widely known and understood. Symptoms like excessive sleepiness and fatigue mimic the effects of daily life for many people, and may seem unremarkable. Onset is usually between 15 and 25, which also prolongs diagnosis, due to a change in sleep patterns and habits around this time of life.

The Excessive Daytime Sleepiness or EDS, of narcolepsy causes people to fall asleep during the day, regardless of the amount of sleep they get at night. Falling asleep can be irresistible, as well as abrupt. Sleepiness attacks can also come on gradually, and when resisted result in the individual becoming increasingly unaware of their actions until they are in a state of automatic behaviour.

Like anyone who is sleep deprived, people with narcolepsy may notice emotional fluctuations and loss of coordination. They often feel tired most of the time, using words such as sleepiness, tiredness, lack of energy, exhaustion or a combination of these feelings to describe their experience.

Hypnogogic Hallucinations are intense, vivid dreams, which are often accompanied by frightening auditory, visual and tactile sensations, usually occurring as one is awakening or going to sleep. They are difficult to distinguish from reality.

Sleep Paralysis is the inability to move when awakening or going to sleep. This may be brief, but can also last for several minutes. Multiple attacks may occur. This can be terrifying, especially when occurring with a frightening hypnogogic hallucination.

One symptom unique to narcolepsy is Cataplexy, which is an abrupt loss of muscle tone, brought on by emotional arousal. Telling a joke, getting annoyed, speaking in public, and performing, among others, can all bring on a cataplectic attack. Attacks range from a brief sensation of weakness in the neck or knees, to total physical collapse, followed by an inability to move that may last for several minutes. Often the head or jaw may sag, or the knees buckle. This is not to be confused with fainting or having a seizure. The individual remains alert and conscious, but is not able to communicate clearly.

People with narcolepsy have abnormal sleep patterns, caused by an impaired ability to regulate the sleep/wake and REM/non-REM cycles. Research has shown that this is, at least in part, due to a deficiency of the neurotransmitter hypocretin, or orexin. Unlike most people, those with narcolepsy enter REM stage sleep early, without going through the normal sequence of sleep stages. They often wake in the night resulting in disrupted night time sleep.

Other events that take place during normal REM sleep parallel the symptoms of narcolepsy: the body becomes immobile as in sleep paralysis, and muscle tone decreases as in cataplexy. These symptoms in narcoleptics are thought to be inappropriate manifestation of these characteristics of REM sleep. The fact that people with narcolepsy often spend more time in REM sleep than an average person means they dream frequently and vividly, perhaps more than others.

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