Greys seen during OOB or astral projection

First off I've never seen ufo's at all or anything similar like that ... but at times when I listen to a biaural beats, I've had experiences of leaving my body and feeling myself detached away from it, sometimes it's so dark I can't actually "see" anything but I feel myself far away from where I'm sleeping, other times I can see things even though it may be night outside, it looks 'bright' in a unusual way, not like the kind of light you would usually see. Usually before this happens I hear some sort of ringing or buzzing that gets louder and comes in patterns. The times I've actually been able to move around freely I've only been walking around, until recently when I had an OOB experience when I saw something standing near the foot of my bed that was out of focus with whitish skin and large eyes, the only thing I could say it would resemble is a alien grey.
Other times when I've had OOB I've seen similar things floating through the sky over houses or just wandering around ... I was wondering if this has happened to anyone else?