My oldest kitty is a 3 year old male tabby named Donny. Every night at 10:30pm he comes in to wherever I am and meows at me. It took me a few days to realize he was telling me it was time to go to bed. Once I figured that out, the next night he came to meow, I went straight to bed and he curled up in his usual place at my feet and snoozed through the night. He's already been after me once tonight and is now positioned on top of my monitor showing me how sleepy he is and that it's bedtime.