How are drowsiness, excessive sleepiness, somnolence, hypersomnolence, and hypersomnia different?

This article was first published on March 1, 2024. It was last reviewed, updated, or edited on March 1, 2024. When asked a question about a patient, I needed to clarify what exactly the problem was that was being described as “hypersomnia”. I got frustrated by trying to clarify the differences between a number of…