Brain scans reveal how to enters a psychedelic-like trance without drugs

But I think what psychologically helps is also doing this not in bed, if possible, because we have bed mostly associated with sleep.

But yes, it certainly requires some focus on not allowing oneself to sleep.

2) Experiential approach through any activity (eg. Bhakti/Tantra/Hatha etc.) also called Laya Yoga (i.e. yoga of dissolution) where one "dissolves" one's identity (i.e. no experiencer nor object of experience) so only the pure experience remains. See the sections on Laya at https://en.wikipedia.org/wiki/Yoga , https://en.wikipedia.org/wiki/Kundalini_yoga and https://en.wikipedia.org/wiki/Hatha_yoga

3) Book of Techniques; Vijñāna Bhairava Tantra - https://en.wikipedia.org/wiki/Vij%C3%B1%C4%81na_Bhairava_Tan...

4) For a simple method to get started and more details, see my comment chain here - https://news.ycombinator.com/item?id=41537499

There are a spectrum of "Consciousness States" which can be partitioned into two categories viz. 1) the three well-known ones i.e. Wakeful, Dreaming and Deep Sleep 2) All the others whether self-induced or externally-induced viz. chemically (eg. drugs/anesthesia), electromagnetically etc.

The model to use as a framework is that of "Raising the Kundalini" (from Muladhara chakra to Sahasrara chakra) which you can assume for now to be an allegory for moving through a trajectory of consciousness states from "normal" to "supra-normal" (can only be experienced and cannot be precisely defined). The major "stages" in this path are at the Chakras which are precisely defined with geometrical patterns, visual imagery, internal sensations similar to vibrations produced by different sounds; viz. specific coloured luminous figures (aka deities), polygons with different 3/4/5/6/etc sides (aka lotuses with different no. of petals), sound vibrations mapped to syllables in the Sanskrit language etc.

The experience(s) of the woman described in the article (assuming it is legit) checks many of the above viz. "She described experiencing vivid internal imagery, alteration of her body schema, changes in agency, and a deep sense of unity", "it begins with intricate geometric and luminous imagery and culminates in a lucid, expansive state of unity and serenity", "she reported the emergence of a violet coloration replacing her dark visual field, followed by the gradual appearance of a yellow-violet hexagonal lattice that she perceived as a structured pattern floating “in the air” around her", "The hexagonal network coupled with rhythmic violet pulses remained the most stable phenomenological motif across all 20 sessions."

My only scepticism is that the article reads "a little too pat" (i have yet to read the original paper) and makes everything seem a "done deal" (i.e. known) in a domain where inherently there can be no objectivity. For example; while the brain imaging shows a specific set of activities (i.e. objective) their correlation to a specific description is based solely on the woman's self-reporting (i.e. subjective).