Klaas Vaak, also known as Klaas de Dromer, is a character from Dutch folklore who is associated with sleep and dreams. He is often depicted as a kind old man who brings sleep to children by sprinkling them with magical sand. This sand helps them fall asleep and have pleasant dreams, making him a beloved figure in bedtime stories. In the Netherlands, Klaas Vaak is similar to the Sandman in other cultures. He is often featured in children's literature and is a symbol of comfort and safety during the night. His presence reassures children that they will have sweet dreams and wake up refreshed.