<prompt> What is a hypnopompic hallucinationIf experienced while falling asleepIf experienced while awakeningAfter head traumaAfter convulsion  <response>: Enquire whether the hallucinations occurred during wakefulness, or were they hypnagogic occurring while going to sleep andor hypnopompic occurring while getting up from sleep hallucinations. this is a type of hallucination that presents in NARCOLEPSY , the major cause of narcolepsy is HYPOCRETIN DEFICIENCY a type of sleep disorder where there is hypnogogic hallucinations hypnopompic hallucinations sleep paralysis hypersomnia cataplexy sudden loss of muscle tone due to emotional stimulus Ref: a sho textbook of psychiatry, Niraj Ahuja,7th edition, pg no.13 