Some get trouble if they sleep in their back, others get trouble if they sleep on the side. Very hard to know how you actually sleep during night.
As an experimental feature this app could also have a video recording mode which records what position you sleep in and how you move when you sleep and how your body reacts when snoring. When to start recording could be determined by movement detected by sonar.
Sleeping in different position (supine, side, or belly) can affect how well one sleeps. Since body position can change throughout the night, it would be nice to be able to record this. @Shelluzo suggested video as a feature request. A closely related feature request I have as an alternative is to use an accelerometer strapped to the chest (e.g., using the Polar H10) to detect body position. I would imagine this would be drastically simpler than processing video feed. Having those time series data would be useful to see changes in body orientation throughout the night.