Does your cat have your sleeping habits?
 

My pussy used to be an early bird. She used to go to bed way before I
did and wake around 4 or 5 in the morning. After finding it
impossible to wake me to let her out of the house, she is now a night
owl like me. Now I have to get her up to get her out of the house.
If I let her sleep too late she ends up getting in 2am. Some nights
she doesn't even come in till morning and then sleep all day. Other
nights I'm in bed and asleep and find her next to me when I wake.