Hallucinations and Sleep Paralysis
People with narcolepsy can have vivid, dream-like hallucinations while falling asleep or as they are waking up. During these episodes, the visions feel real—for example, seeing a person in the bedroom. The hallucinations are called hypnagogic if they happen while falling asleep, and hypnopompic if they happen while waking up.
At the same time, people with narcolepsy experience paralysis as they’re falling asleep or waking up. This is the normal muscle paralysis associated with rapid eye movement (REM) sleep, but occurring at the wrong time. Although the paralysis usually only lasts a few seconds, it can be very frightening, especially in combination with hallucinations.
Hallucinations and paralysis are caused by a disrupted boundary between dream sleep and wakefulness. Rather than gradually reaching REM sleep at the end of a sleep cycle, a person with narcolepsy can enter REM immediately. This means the dreaming and muscle paralysis of REM will occur directly from a waking state. Like sleepiness, these symptoms can sometimes be seen in those without narcolepsy, too.