[hĭp-năp′ə-gŏjĭk, -gōjĭk]
  1. Causing wakefulness; preventing sleep.
  2. Of or relating to a state similar to the hypnagogic through which the mind passes while coming out of sleep.
  3. Relating to the images or hallucinations sometimes perceived during this state.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.