Soporific (8)
(Other definitions for hypnotic that I've seen before include "bewitching" , "soporific" , "Mesmerizing" , "spell-binding" , "Trance-inducing" .)
'soporific' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for comatose that I've seen before include "Come to as in drowsy condition" , "Deeply unconscious" , "Sandman called" , "Senseless, unconscious" , "Fast asleep" .)