and Michel Houellebecq seems to use similar process:

INTERVIEWER

What is your writing schedule now?

HOUELLEBECQ

I wake up during the night around one a.m. I write half-awake in a semi-conscious state. Progressively, as I drink coffee, I become more conscious. And I write until I’m sick of it.

This explains a lot about Houellebecq's writing.

It sound interesting, but I never have heard it before and I can't find it in the link or in Google. Is it in the book? Is there other source? (Creativity advisors are sometime too creative.)

This is also mentioned in the Coursera course "Learning How to Learn" (https://www.coursera.org/learn/learning-how-to-learn). Though I don't recall/know what their source is. "Dali Sleep Technique" turns up many hits in your favorite web browser, however.

it is in "50 Secrets of Magic Craftsmanship" a bit after the "Three rules for controlling your dreams".

Edit: Search for the sentence "In this posture, you must hold a heavy key which you will keep suspended, delicately pressed between the extremities of the thumb and forefinger of your left hand." and look at the google book result, you can read the page 36.

John Cleese mentions this process as being done as well by Thomas Edison in his Talk at Google: https://www.youtube.com/watch?v=2-p44-9S4O0&t=9m39s

If you're reclined (on your back) a bamboo chop stick (or light metal tube that's a bit bigger held with the tip a couple of inches above your forehead works. Make sure your thumb (and no fingers) are below the stick so it will fall.

I had heard Edison did this.