hypnagogic« Back to Glossary IndexHypnagogic is the transition from wakefulness to falling asleep.Related Articles: About Related Sleep DisordersGlossary: hypnagogic hallucinationsGlossary: narcolepsyAsk the Doctor: Narcolepsy vs Idiopathic HypersomniaIt’s a Fine Line Between Type 2 Narcolepsy and Idiopathic Hypersomnia… and It’s Getting Even Finer