Hypnagogic

adjective

hyp·​na·​go·​gic

 | \ ˌhip-nə-ˈgä-jik , -ˈgō- \

variants: or less commonly hyp​no​go​gic

Collegiate Definition:

 of, relating to, or occurring in the period of drowsiness im-mediately preceding sleep.

hypnagogic hallucinations