One thing I've found (which I'm not currently doing as well as before) is if I set one time to wake up each day and actually get out of bed (no snooze), I start waking up more and more refreshed. It could be 5, it could be 8, but if I am consistant, it doesn't matter the time, I wake up and am not groggy.

So, could be useful for super early wakeups like 5 AM.