Concerning the drowsiness one commonly feels before sleep , the transitional state preceding sleep , and also the hallucinations that may occur at that time. See the entire definition of Hypnagogic
This is the border state of consciousness between sleep and wakefulness. This state has been found to be accompanied by a distinct physiological characteristic, relaxation, decreased EEG tracings showing theta waves production, slow eye movements (SEM's), less activity of the frontalis (muscle of the forehead).
hip-nuh-goj'ick 1. Denoting a transitional state, related to the hypnoidal, preceding the onset of sleep; applied also to various hallucinations that may manifest themselves at that time. 2. Inducing sleep; hypnotic. Term: Definition: Description: . . . . .