How are out of body occurrences explained? (Astral projection)?

So many people have experienced OBE's that it's simply unexplained at the moment. Many people even claim to induce OBE's whenever they want. Ive experimented a little. There is a process of making your body fall asleep while remaining conscious. This actually works and you sometimes hear thing, even have stong vibrations throughout your body to the point it feel like your whole bed is rocking back in forth. Its a scary experience if you dont understand it.