Cats may sleep more in winter because of a few reasons such as: a) colder temperatures during winter can make it more comfortable for fluffy balls to curl up and conserve heat by sleeping. b) In winter, when food can be harder to find, animals like cats have a natural instinct to save energy and do this by by sleeping more. However, not all cats sleep a lot more in winter. Some cats may have different habits depending on their personality and the environment they're in.