It's been occurring more and more frequently and I'm almost to the point where I'm afraid to try and sleep because it might happen again.
Its called sleep paralysis (google it and you'll know that its a natural condition while one is asleep) and you should feel happy and consider yourself lucky that you can remain conscious while this is happening, instead of being afraid, because you can use it for projecting yourself out of your body easily.
Just follow any suitable exit technique while you are in SP.
Best of luck !