My 5-month-old kitten has been sleeping more and playing less lately. She is playful in the am, then basically naps from around 1 pm until 10 pm, with only short wakes to eat and use the litter box. Late at night she starts playing again. I am not sure how much she also sleeps overnight. She does sleep with us at least some. I know cats are nocturnal, but is this an excessive amount of sleeping?