A cat curling up into a ball while sleeping may be caused by feeling cold, distrusting the surrounding environment, or sleeping habits. It is a normal phenomenon. Don’t worry. Most cats will curl up into a ball while sleeping, but you need to pay attention to helping the cat. Keep warm to prevent cats from catching colds.
Tips:
Cats’ bodies are very soft, so they can sleep in many positions. The most common ones are curled up into a ball, Lie on your back or sleep with your belly up.