Actually, the way you do it is simple. You want to trick the brain into thinking you are falling asleep. But you want to stay awake when the mind separates from the body. This is a very natural thing and it happens every time you dream. If it did not happen you would dream about running and wake up miles from your bed. The brain disengages from the body, all but autonomic functions.
If you are an experienced meditator you can sit or lie in your most comfortable position.
What you want to do is eliminate all external stimuli to the body. Loose or no clothing and earplugs help.
If you are in a lying position, lay on a hard floor. Put a towel on the floor and roll another towel up to place under your neck.
Lie on the floor, arms at your sides at about a 45-degree angle. As comfortable as possible. I like my palm up but I don’t imagine it matters.
Now you want to focus all of your attention on the spot just between and a little above your eyebrows. Keep your attention there. You will itch, twitch, get uncomfortable, and even honey, but keep your attention in that one spot. Do not let your mind wander or wonder.
Now, to keep you focused, the easiest thing to do is to count from 5 to 1. You do not need to do any special breathing. If you know how to breathe in a meditative way, go ahead and do that. (In through the nose and out through the mouth, tongue tip touching the roof of the mouth. ) Cout as you inhale.
Exhale and in your mind repeat, “5…5…5…5…”
Finish the exhale and inhale naturally as you continue the count " 5…5…5…5"
Complete the inhale and exhale …“4…4…4…4…”
How many times you say the number does not matter.
Go to 3, 2, 1, and start over. (This is a whole lot harder than you imagine.)
Keep your mind focused and do not allow it to wonder. If you Wanter off, just bring it back to the center and continue the count from wherever you think you left off. Don’t stress about it.
Last thing: As you exhale, try to sense your body relaxing on the floor. Sinking. You are not altering your concentration point. You are not dividing your attention. You exhale, remain focused, and sink into the floor.
This works best if it is done at the same time every day. A time when you are NOT tired is best so that you do not fall asleep. An empty stomach also seems to help.
WHAT WILL HAPPEN:
You will hear a roaring train. The kind of sound you would experience if you were standing next to a train that was rushing by. You will feel the clothing on your body flutter as if you were on a motorbike driving into a windstorm. (IMPORTANT: You must maintain the count. Keep breathing. )
Next comes a dropping sensation. In my case, I flip, my feet over my head. (The count must be maintained.)
This is the point of separation and the appearance of the “so-called, astral body.” Minus all stimulation, the brain creates its own stimulation. It creates the astral body.
This is nothing but a brain state.
Counting will cease at this point as you are no longer aware of your own body lying on the floor. You will believe you are in the astral body."
What you are actually doing is putting your body to sleep while your mind stays active. This is what happens in sleep paralysis. It is a completely natural phenomenon. And instead of creating a phantom limb, as in phantom limb syndrome, your brain merely creates an entire body. Again, nothing unnatural, spiritual, or magical about any of this.
With consistent practice, I think anyone can experience this in about 30 days.
One caveat: If you are trying to have an out-of-body experience you will defeat yourself. You are feeding your brain as you practice this. Don’t think, I want this or that to happen. Just breathe and count. Every time you think or pull your attention from the count for any reason, you are disrupting the exercise. Only breath, count, and sink. Nothing more.
Good Luck.