In the arena of religious, spiritual and psychological healing, there are two different approaches: Under control vs out of control. Usually when one thinks of "under control", one usually have a cognitive or rational approach in mind: the situation is analyzed with logic and everything has to be proved scientifically before acceptable as a valid approach. The most extreme position is Behaviorism as presented by B.F. Skinner, in which the concept of mind is totally dispensed with. The psychologist or healer will only care about a patient's behavior and act upon it. Nowadays this approach will mostly be reserved to training mice where the theory was first scientifically studied (animal lovers will not accept this approach even for their pets!). Rational approach is of course important. But if our rational mind alone can solve every problem, there will be no subject called psychology!
Therefore it is true that our cognition is important. And our ego is important too. But our Unconscious comes into picture, making the situation more complicated then we have bargained for: some forces acting behind us even without our knowing! And worse, we tend to rationalize the compelling influence of such "dark influence" by distortion the reality as we perceive it - even our healers will be fooled!
The uncontrollable intrusion of our Unconscious prompted many healers to "let things happen by themselves" or "let things go out of control" and hopefully, without undue suppression, our psyche will find its own "correct" route. But generations of psychotherapists of Freudian influence have demonstrated that we can't really trust things will move the way we want them to move if we simply lay-back (literally on a couch if you're having a session with a shrink)! That's why nowadays, THE approach for psychosis is to use psychotic drugs instead of psycho-analysis or hypnosis! (as a side-line: even Jung believed hypnosis was too unpredictable when compared with psycho-analysis, as far as prognosis is concern! It might be nice to play with hypnosis for the mentally-sounds, but don't depend on it for any psychological treatment, that seems to be in line Jung's advice!)
Some alternative healing (alternative to psycho-therapeutic treatment) still uses the "out of (our cognitive) control" approach. Patients (or clients or students or disciples) go to ceremonies (religious or spiritual) or treatment sessions and will be induced into trance-like situation or simply go into hypnotic conditions using the services of a hypnotist. Going into such trance like situation oftentimes does give one some good relief and comfort: sometimes like going for a good massage in a spa, but for course, those who can the better our of a good massage will likely not taking the trouble going into a trance like situation.
How does Taoist deep meditation (or Neidan) fit into this picture of healing? Non-practitioners sometimes may think that Taoist Neidan will get one into a trance like situation during meditation. But they are wrong. Indeed there are some branches of "Taoist practice" that will induce people going into a trance-like state of mind (and presumably very comfortable too!) The most notable one is "Ghost-boxing" (神打). Here a practitioner will be induced into a trance-like mentality, and the demonstration of being on-trance (Chinese are pragmatic, they need visible proof) is that once one's Immortal-guru has entered one's body, one can withstand chopping by sharp edges without pain and without being hurt (but once in a while, accident does happen and the practitioner will be sent to ER).
Classic Taoist Neidan (deep meditation) is everything but trance-like. Neidan aims at combining one's body (身) essence and heart (心) essence. How to make this happen? It has to be under the subtle influence of one's mind (higher self) 意。 The latter can only be subtly controlled by the practitioner when he or she is under a (Taoist) meditative zone. And a prerequisite to have such higher-level control is through morality training of studying the classics as well as putting such teachings into daily lives.
Letting one's mind out go of control can actually be dangerous for certain people who are prone to psychotic onset. Should such situation be allowed to happen under one's own free-will, psychologists like Carl Jung will call it "self-induced psychosis". And nobody wants that! So, practitioners beware.