Ok here is the visualisation:
You lie down, get in sleeping position.
Then you visualise walking towards a flight of stairs, which is going down.
The first step lights up red when you step on it, and the space is filled with red light...red like [insert red item from your memory]. I might think, red like a honey crisp apple, and then visualise the red light and the red apple.
The second step lights up orange, and the space is filled with orange light...orange like [insert orange item from your memory]. I might think, orange like carrot juice, and then visualise the orange light and the carrot juice.
The third step is yellow...and repeat visualisation
The fourth is green.... repeat visualiation for green....
The fifth is blue...repeat visualisation for blue...
The sixth is lilac purple....repeat visualiation...
The seventh is a darker purple...repeat visualisation...
The bottom of the stairs is black...so when you get there, you visualise space and everything as being pitch black, and now you walk down this dark black hallway and at the end of the long hallway is a small door, just big enough for you to crawl through.
You have a key of some sort to open the door, and only you have access to it. Could be a physical key, a pin code, a touch...whatever. But you have the key.
You unlock the door and squeeze over into the other world where everything and every symbol is yours. My counselor said his world was like a cottage at the edge of the sea and all the animals would come be with him, and he had shelving in his cottage where he put different things.
For me I tend to wander into a changing universe, and there are spirits (good and bad) to greet and contend with. My world is less safe, less static, but thats just what suits me.
Your world, you can do/be whatever in it....
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Usually I fall asleep before I get to the blue step. But even if I dont, it relaxes me. I was surprised that it worked.