Yeah, it's true about going to sleep earlier. Your body has its own time clock in the Pons (part of the brain that controls the sleep-wake cycle), and it generally knows what time it is. Before midnight-2AM is the time that the body regenerates most of its cells and can be considered "healing time" so it's much more important to go to sleep earlier than to get extra sleep by sleeping in. This info is off the top of my head, but I heard it pretty recently in a health report, so I don't know if I got the info down right.

Here's something funny: My body has an incredibly accurate time clock. I don't know if it happens to anyone else, but I always wake up exactly one minute before my alarm clock goes off. I hate the sound of the beeping in the morning, so I've made it a habit of turning it off right before it goes off. It doesn't matter when I go to bed; as long as Im rested enough to be able to wake up, I find myself doing this. Just wondering - does this happen others?