adjective. Inducing sleep; soporific.

adjective. Of, relating to, or occurring in the state of intermediate consciousness preceding sleep.

Leading to sleep; inducing sleep; hypnotic.

adjective. Leading to sleep; -- applied to the illusions of one who is half asleep.

adjective. That induces sleep; soporific, somniferous.

adjective. That accompanies falling asleep; especially, pertaining to the semi-conscious period immediately preceding sleep.

adjective. sleep inducing

"Because the existing word hypnagogic means “of, relating to, or occurring in the state of intermediate consciousness preceding sleep,” and hypnopompic means “of or relating to the partially conscious state that precedes complete awakening from sleep,” many people came up with hyp - coinages."

depressant  

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