As cats always sleep, do you ever wonder if they have dreams? Cats sleep roughly 16-18 hours a day. Like humans, they experience Rapid Eye Movement (REM) sleep. The REM stage is when most dreaming occurs. This happens when they are relaxed enough to enter a deep sleep. So we know now that cats do dream, but what do cats dream about when they sleep? Just like humans, the dreams of cats are often based on realistic experience. Also, they may have sweet dreams and nightmares just like we do.