- Excessive daytime sleepiness
- Cataplexy (brief, sudden loss of muscle strength)
- Sleep paralysis, and
- Hypnagogic hallucinations
EXCESSIVE DAYTIME SLEEPINESS
Daytime sleepiness is present in all narcoleptics and is usually the first symptom that appears. People with narcolepsy report feeling continually tired or sleepy all the time.
They tend to fall asleep not only in situations in which many people normally feel sleepy (after meals or during a dull lecture) but also when most people would remain awake (while having a conversation, writing a letter or watching a movie).
These “naps” tend to be short and may be refreshing, at least for a short period of time.
People with narcolepsy may become drowsy or feel foggy at very unusual times, even in dangerous situation such as while driving.
Attacks of cataplexy – sudden, brief losses of muscle strength – are sometimes the first symptom of narcolepsy, but more often develop months or years after the onset of sleepiness.
Cataplexy can be mild – such as a brief feeling of weakness in the knees – or it may cause a complete physical collapse, resulting in a fall. A person having such an attack is fully awake and knows what is happening.
Cataplexy is usually triggered by strong emotion, such as laughter, anger or surprise. In some individuals, simply remembering or anticipating an emotional or anxiety producing situation can produce attacks.
Sleep paralysis is also a brief loss of muscle strength but it occurs when a person if falling asleep or waking up. The person may be somewhat aware of his or her surroundings, but is unable to move or speak.
Sleep paralysis can be frightening but is not dangerous since the muscles that maintain life (the main breathing muscles and the heart) are not affected.
Hypnagogic hallucinations are vivid dreams that occur when a person is drowsy. The hallucinations may involve disturbing images or sounds such as of strange animals or prowlers.
These hallucinations may be frightening because the person is partly awake but has no control over the events. The dreams can also be upsetting if they are mistaken for hallucinations caused by mental illness.