The hypnagogic state is the transitional period between wakefulness and sleep during which sensory perceptions can occur. This review compiles recent scientific literature on hypnagogia, discussing terminology and distinguishing it from related phenomena, and reports its prevalence. It evaluates six future directions proposed by Schacter (1976) and adds three new ones: understanding the emotional quality of hypnagogic states, why they occur so often in visual and kinaesthetic modalities, and their purpose. Research has advanced greatly, bringing us closer to demystifying this state.
Hypnagogic states—vivid experiences during the transition from wakefulness to sleep—were reported by 80.2% of 4,456 participants in a questionnaire study, with higher prevalence in women than men. Kinaesthetic and visual experiences were most common, while auditory, tactile, olfactory, and gustatory ones were less frequent. These states were less prevalent than dreams and showed distinct modality profiles, but matched dreams in emotional quality, irritation, and vividness. The findings indicate hypnagogic states are widespread and share key features with dreaming.