[Adiamant]

Most people that have spontaneous OBEs tend to not sleep deeply for very long- the light state that makes you not go deep is also the perfect state for OBEs. So the more you worry about them the more you will have them.
If you can't simply 'not worry' about them, I recommend you start learning how to get them on purpose, and the ability to do them at will will give you control over the process.
If it indeed is your Guardian Angel (or Higher Self) guiding you through them, there may be a higher calling to your experiences, and that reinforces my idea that you're supposed to have them and to learn control over them.