Why do cats sleep in their litter box?

Cats sleep in their litter boxes to feel more secure and less anxious. This is because the litter smells of them. It creates a comfort zone. Cats might sleep on the litter itself or near the litter. I have seen this at cat shows. Show cats can become anxious, particularly cats new to the scene. Breeders sometimes put curtains and cloths in the and around the cage. Show cats might burrow into the cloth in the cage to hide or sleep on the litter in the cage. Breeders have small litter trays in the large show cat cages.

British Shorthair grey tabby show cat at a show sleeping on grey litter. Photo: Michael

When I introduced my three-legged boy cat, Charlie, to the household, my elderly lady cat used to sleep by the litter tray or occasionally in it until she became more settled with Charlie's presence.