Hypnagogic or hypnopompic hallucinations are visual, tactile, auditory, or other sensory events, usually brief but occasionally prolonged, that occur at the transition from wakefulness to sleep (hypnagogic) or from sleep to wakefulness (hypnopompic).
This is a companion discussion topic for the original article at https://patient.info/doctor/history-examination/hypnagogic-hallucinations