I'm always amazed at their internal clock -- if you feed them at 5 p.m. everyday, they sure know when that time rolls around. It's funny, too, cause they have to adjust to Daylight Saving Time just like us.
When Fred was alive, he'd come and wake us up if we slept later than usual. He'd usually bug Brian, though, as he gives in quicker than I do. Before he got old and got diabetes, he was a heavy cat -- about 11 lbs. He'd come and climb on Brian's pillow and then lay down right on top of his head. Brian said it felt like a bowling ball on top of his head.
Lola, regardless of whether she sleeps on the bed with us, downstairs or on the third floor, often wakes us up about 2:30 or 3 a.m. with loud meowing, usually from the bottom of the stairs. Often in the morning, there will be two or three of her little toys right outside the bedroom door (which is propped open so she could come in if she wanted). Seeing those toys always makes me laugh, as I know she must've been up playing around that time. She's just hollering for someone to join her!