Every cat is different. My cat Bella used to sleep probably about 17-18 hours a day. My kitten loves playing, so she is much more active, whereas my other two cats sleep probably about 12 hours a day. Some cats can and will sleep up to about 20 hours a day, though
Feeby (16+yo) probably sleeps at least 18-20 hours a day. She wakes up to wait to be fed breakfast, use the litter box, and maybe will check out the house for something 'new and exciting' (which isn't usually happening), and then goes back to sleep. In her old age, she is the epitome of a nocturnal animal - she naps off and on overnight with multiple changes of location on our bed, but yet can stay still in a paper bag for 4 or so hours in a row during the day without budging.
Isn't it impossible to say, because who knows how much they sleep when you sleep? Even during the day its really hard because of cat naps for short intervals. All I know is that in the mornings, my 5 year old cat is really desperate to be on the lap, but around 11 or 12 he starts napping on and off, and doesn't usually try for the lap again until 5 or so. I don't know that he has specific regular awake periods per se, but he does actively play with the 1 y.o. cat at times. Maybe 8 or 9 pm would be an active period. The one year old is even harder for me to track her sleep, since she doesn't always seek attention when she is up.