It is a psychological state, and not everyone can do it deeply. Indeed, a significant percentage of folks who do it are deeply suggestable. so why are they proposing it for patients as a value free treatment?
It is related to the deep concentration one gets when watching a film (but not a movie on tv, where there are distractions) or engaged in playing music or making art, or reading a book in a quiet place, or saying the rosary in a quiet room. It opens the deeper psychological self in some people to enhance creativity.
But it can be a spiritual thing. Indeed, the prayer of quiet or the Jesus prayer does the same thing. As Father Dubet on EWTN points out , the buddhist mindfulness goes into oneself, but Christian prayer is supposed to be spontaneous, not forced, and occur when one is praying or reading the bible, and has Jesus, not self, as the object of the meditation.
If one believes in a reality beyond the material, there is a danger of not just finding God or a good angel, but of finding a demon disguised as an angel. This also could mean finding the evil in one's deeper self:
Or, as one sci fi movie put it: Meeting the demons of the id.
I used self hypnosis for cigarette control, but refused to hypnotize one man...I sensed he was holding in something dangerous, and that hypnosis might open the door...later it turned out he was full of anger at his father, and got a bit violent when given prozac, which allowed his anger to surface. Psychotherapy can do this also. People think psychological manipulation has no "side effects" but this is not true, especially in the ten percent of the population who are easily hypnotized and easily suggestible even when not under hypnosis.... One is reminded of the hypnosis experiments of Freud, or when a professor lacked a patient to use for his students hypnotized one of the cooks, who was then manipulated into all sorts of conversion reactions and insanity from his suggestions.
So they are now pushing mindfulness as psychological treatment for depression.
But unless they do a double blind study of maybe having the patients pray in a rosary group I'll be sceptical.
One reason I hate the modern sitting in a circle holding hands and praying is that you end up not concentrating on God. In a rosary group, or praying the office in common, you concentrate on God.
And don't get me started on psychological group therapy where you are supposed to tell all your secrets. We were forced into this in medical school and I usually told lies and when possible arranged for the nurses to page me out for an "emergency" because my inner self was simply not any of their business.