A spiteful and vicious creature, Somnolens was jealous of the daughter of the local King and tainted a spindle with the Draught of Living Death. She then tricked the young princess into pricking her finger on it, sending her into a deep sleep. Her plan was foiled, however, by a young wizard who smeared his lips with Wiggenweld Potion, and then kissed the princess, curing her and bringing her out of the sleep. Her story appears to be the source of inspiration for the Muggle fairy tale, Sleeping Beauty.
- Somnolens is a derivation of "somnolence", which means "sleepiness".