Although I’ve never tried this particular app, I’m a huge fan of a competitor (reviewed here). Both share a similar concept: keep your iPhone plugged in, facedown, resting in your bed, with the app running. The iPhone’s accelerometer records and graphs your movements throughout the night (sleep nerds unite!). As your movements in the bed become more noticeable closer to your scheduled alarm time, the app’s alarms goes off. The theory is that you are cycling from a deeper sleep to lighter sleep, and when you’re moving, you’re at a lighter sleep and the alarm will be less disruptive.
Sleep Time’s competitor is my primary alarm clock – and has been for several years. Out of fairness, I did decide to grab Sleep Time when the price dropped to free. If you do too, please share your experiences.
Sleep Time is currently free at the App Store (link)