I'm using Sleep Cycle on my iPhone and it works like a charm actually. Downside is that you should keep it in bed so it can measure your sleep, but the vibratio

I'm using Sleep Cycle on my iPhone and it works like a charm actually. Downside is that you should keep it in bed so it can measure your sleep, but the vibration of my phone and alarm sounds are always on the right time. It's my only alarm, in stead of the 7 alarms I used before (at the same time!)