The other morning one of our cats wanted us to get up early, and sat on DH's chest, purring loudly and kneading. DH ignored her. A few minutes later, his radio alarm went off, and he reached over and hit 'snooze'. She wandered onto the bedside table, sniffed around, then came back on his chest. Five minutes later, the alarm went off again and he hit 'snooze' again. She watched him, walked over and sat ON the alarm clock, and padded around with her feet until the radio kicked in. Then she jumped down and went and sat by the door, looking at us expectantly (and looking very pleased with herself). 
The next morning we were woked very very early by his radio... and a very smug looking cat.