[noodle]

Your "sleep" clock works mainly on body heat. The hotter your body is, the more energy it has.

The best way to set a sleep clock is by doing sport. Do some jogging in the morning (at a time you wish to wake up), and after a week, you'll automatically be waking up at that time without the need of an alarm.

During the day, try to get as much sunlight as you can. This is extremely important also.

Anyway, I don't know how old you are, but the 8 hour sleep a day thing is nonsense for adults. For younger people, you need your 8 hours. You'll be fine by sleeping 5 or 6 hours a day, and according to a study done by the University of California, you'll probably end up living longer.

I think someone said that you shouldn't take a nap. That's nonsense also. We're actually meant to take an hour or two nap around mid-day, but because of the modern lifestyle, people have forgotten about it or are just too busy for it!