iOS Bedtime not tracking sleep accurately

Think about sleep tracking for a moment. How does it work? Most sleep tracking apps require that you wear something that senses when you move. This is a very poor way of measuring sleep; if you lie still it will record that you are asleep when you are actually awake. If you actually are asleep many people move around in their sleep; for them it will show they are awake when they are not. The iPhone itself has no way to track your sleep; it depends on an external sleep tracking device that syncs to the iPhone. The information will be only as accurate as the device you are using to track your sleep. The most accurate sleep trackers are essentially EEG devices that measure your brainwaves.

While there are sleep tracking apps that don't require you to wear anything they really only work if you sleep alone.

If you set it off of the bed and on the night stand it will show you sleeping longer. when you move the bed moves and when the phone moves it thinks you are awake. it is not intended to be a medical device to track sleeping in that way. It essentially tracks non-use.

Are you interacting with the device at all during that time?