sleep position trainer
Japanese for 'trainer', and that's just what it does.
Torena is a sleep position trainer app for Android built by Koalative. It is created to help out users with positional sleep apnea, but it really serves any scenario where controlling sleep positions is important for a good night's rest, e.g. while recovering after surgery where you should avoid specific sleep positions. It allows you to train your body to avoid a specific sleep position by detecting the sleep position with your smartphone and triggering an alarm. By doing so, your body will learn to avoid this position, ensuring better nights.