hyp·na·gog·ic / ˌhipnəˈgäjik; -ˈgō-/ (also hyp·no·gog·ic) • adj. Psychol. of or relating to the state immediately before falling asleep.DERIVATIVES: hyp·na·gog·i·a n.

hypnagogic (hip-nă-goj-ik) adj. relating to the period immediately before falling asleep. h. imagery the production of vivid mental images just before falling asleep. h. hallucination a vivid and intense auditory or visual hallucination occurring at the beginning of sleep in 30–60% of patients with narcolepsy.