how refreshed you are when you wake up is more a function of when you wake up relative to your sleep cycles. you can do two things -- set yourself a consistent

how refreshed you are when you wake up is more a function of when you wake up relative to your sleep cycles. you can do two things -- set yourself a consistent, permanent sleep schedule (always go to bed and wake up at the same time), or research your own sleep patterns to try and determine about when you hit phase 2 non-REM sleep, and set your alarm clock accordingly.