wanted to get some advice/explanation on this phenomenon - just saw a good thread from Ian ( https://www.dharmaoverground.org/discussion/-/message_boards/message/22310849 ) but I had some specific questions/angles which I didn't see in that thread....
something that's been happening to me for a few years.

Basically, I'm asleep, and I wake up, but I'm not actually awake. I'm lying there having the sense of a body in a bed, and my awareness is there, but some part of me knows I'm actually asleep. I don't even know how I know this, it's just a feeling. (is this sleep paralysis)?

What I do then is I make a small effort to listen to the what is normally the background hiss of silence - the white noise vibration which is always there in waking states. I fall back into the back/centre of the head maybe down the spine ? and the noise becomes a really loud white-noisy-screamy-digital roar (imagine in a sci-fi movie, if a big alien-AI-robot dies, the kind of scream it would emit), and my consciousness begins to peel/lift out of my sleeping body, like peeling a sticker off of something.

If I 'succeed' in this, I am either in my room where I went to sleep, floating, in a lucid dream state
or sometimes as I peel upward out of my body into a some kind of random lucid dream world.

if I 'fail' maybe my body gets stuck peeling up and I end up back in my body actually awake.

This has happened to me for many years, sometimes I go thru phases of doing it quite a lot, sometimes not.
This does feel different somehow to lucid dreaming.

So I guess my questions are

1. Does anyone do this specifically with the sound of silence becoming a roar? what is the deal with that? why does this sound gateway peel the consciousness upward out the body?
2. why is this gateway only available through this false-waking-up sleeping state? can it be accessed in deep meditation too?
3. why does it feel different to a lucid dream? I'm not so experienced in these arts so would appreciate insights
4. any additional info or pointers

thanks DHO

Similar thing happens to me, waking up paralyzed with body vibtrating at high frequency and deafening roar, something like last few seconds before a plane crash I imagine. It used to scare me but now I try to relax and fall through it, either landing in blissful mediation state or lucid dream (getting up and flying though walls) or else "failing" and falling back asleep. I first noticed the body vibrations with teenage anxiety. Now getting into deeper absorptions I feel constant background body vibration, which feels like some kind of baseline anxiety level. I assume it's the same thing as experienced during sleep paralysis and can be portal into other domains. I feel like the anxiety/vibration is slowly decreasing over time with deeper absorptions/more relaxation, though it would be nice to have more LD triggers :-) 

Check Daniel Ingram's compilation:

OBEs are quite different from Lucid Dreams
Astral projection

I have had a few of those experiences, only when in A&P plus practicing Qigong intensely. Check if before the roar you sensed an small ball of energy orbiting your body. It starts in your sacrum/groin. I felt it orbiting in an horizontal plane (X axis, picture a circle in the bed plane), coming in and out of the body, not up and down the body like Taoist's microcosmic orbit. But probably that's only me. You can (gently) order/allow that ball of energy to enter your head and then go to your heart or your feet. When pointing to your heart, the body usually goes up, but your can (gently) order/allow to go (deep) down. So, you move in the Y axis. When pointing to your feet, the body moves in the Z axis. On two occasions I went into a hole/tunnel (in the Z axis), but just a second later I ended up in floating above bed, then gently falling back to bed. Nice afterglow, slept nicely. 

My theory is that with greater awareness of awareness during waking hours, your brain naturally inclines towards this awareness while asleep and that this experience of white noise and subsequent leaving of your body is just a natural part of the sleeping process that one is normally not aware of. 

I have read Daniel's post about OBE's and lucid dreaming, and I'm still not sure if they are in fact different. I probably am not qualified to say that having your mind so concentrated that you can leave your body while meditatiting vs. it just happening naturally while asleep are the same or not, but feels like its all on the same spectrum. Sometimes I rise out of my body and am in a clear astral-realm version of my room, sometimes I just sink back into darkness, deeper and deeper as the 'noise' fades away. Also, it's not always happening from the sleep paralysis state, very often I will fully wake in the morning and the noise will come as I'm falling back asleep. I don't know if your questions really have any answers, but I'm glad to know that they are arising for you. I'm pretty sure everyone can tap into them with the intention to cultivate awareness while sleeping and, hopefully, can help provide insight into the true nature of reality. 

Recently the 'sound' has been less prevelant and I've felt it more as a  tension experienced in or around the head, I'd even say like a magnetic force. When this sound-like tension arises, I can relax it with effort, just like I'm relaxing a muscle, which causes the sound to increase and as it does I feel a pushing or pulling or falling away from my physical sleeping body, and once I'm fully out, the sound and tension are gone and effort is no longer needed to remain in the state. 

Since posting, I've been more aware of this vibration in meditation and tuning into it intentionally. Last night I experienced it during a more pure lucid dream state, with less of the sleep paralysis aspect. It was still a physical sensation, but I didn't feel as much like I was trapped in my body while being awake, rather I was more aware that I was in a dream and I could play with it. The fear and anxiety were less and there was more fun and bliss, flying around with it and enjoying some cool visuals.

In conclusion, for me at least, I feel like it's the same underlying root anxiety phenomenon being experienced in different modes of consciousness - waking, absorption, dreaming and sleep paralysis (which itself seems to lie on the border of waking, dreaming and sleep). And it does seem to be amenable to intentional investigation ... I'm glad you started this thread thanks :-)