[schrototo]

I've had a sleep cycle alarm clock for a couple of years now (they've been available long before this WakeMate thing, and mine also collects sleep data, altough I guess the WakeMate interface is much nicer) and although it kinda works, don't expect to wake up refreshed if you're shortchanging yourself on sleep. If you're only getting 5 hours of sleep a night you're going to wake up tired no matter what.

Since most of the time I don't really have to get up at a specific time, I usually let myself be woken up by the sunlight, which is the most consistently effective way of waking up refreshed that I've found.