The Diagnostic and Statistical Manual of Mental Disorders (DSM) is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders. In DSM-IV, "Qi-gong Psychotic Reaction" is described as "an acute, time-limited episode characterized by disassociative, paranoid or other psychotic or non-psychotic symptoms....Especially vulnerable are individuals who become overly involved in the practice." In common language, it is usually referred to as chi-kung or kundalini syndrome (that, for practical purposes, refers to the same thing). The question is: what is its cause and how can a practitioner avoid it?
The gist of the matter relates to the important concept of chi-foundation liberation (動氣基) or kundalini awakening. In chi-kung practice, chi-foundation liberation is a legitimate and beneficial objective of every practitioner. The right approach is do it step by step. Metaphorically speaking, and using scientific language, chi should be liberated firstly through osmosis, i.e. chi is to be activated broadly and go into one's body slowly. Secondly it is by diffusion, i.e. when chi-foundation is more liberated, more chi will be channeled inside one's body resulting in some part of the body having a higher concentration of chi. In this situation, a practitioner will need to use his mind (in meditative mode) to direct the chi to areas with less chi, like the physical (from physics) process of diffusion.
It is interesting to note that DSM reads, "Especially vulnerable are individuals who become overly involved in the practice." The question is should one then NOT to "overly involved in the practice" in order to avoid any side effect? The answer is yes and no. Yes, for those who are too eager for speedy improvement but without the necessary knowledge or understanding. No, for those who want to improve further and are armed with the necessary knowledge and understanding, together with the necessary patience.
The question is: what should a practitioner expect when he starts to "overly involved in the practice"? He should expect a, oftentimes quite sudden, flood of massive energy one day or accumulating over a period of time. Metaphorically, it is a like chi flooded over through a hole, rather than through the process of osmosis (through a permeable membrane)! And it is this flooding of chi that causes all the bad effects of a kundalini syndrome (arising from a faulty kundalini awakening) or, in chi-kung lingo, 走火入魔 - fire running wild resulting in possession by evil spirit.
If you have read carefully the last sentence, you may have noticed that the Chinese saying tells you more about what is going on! The next question: A practitioner wants to move further, but how to avoid any pitfall?
Having understood what is happening, it is easy to find a solution, as always. The solution is "The fire (or chi) thus erupted has to be managed, and one consciousness (mind, again in meditative mode) must be focused so that it can control the "spiritual forces" (coming out from the Unconscious) together with the chi (the psychological reality of "spiritual forces" is an affective state that has a high degree of autonomous).
I am touching on an important psychological understanding of the the whole issue. Everybody knows chi means energy, but where does the energy come from? Any serious practitioner (of chi-kung or (Indian or Taoist) yoga) who has attained this stage can feel the power of the energy thus liberated. Moreover (dangerous for the novice, but beneficial to the knowledgeable), once the hole is there, it won't (willingly) close again! First question: what is this energy? First answer: Psyche energy of the Unconscious. Second question: How should one deal with this now unstoppable flow of energy? Second answer: Use it to do some useful task for you! If you think the second answer is mythical, you still don't get it. Let me continue.
Enlightened practitioners of chi-related practices in ancient China knew about the power of liberated chi (I mean through the metaphorical opened hole with flooding chi). A martial art practitioner of the internal type (like tai-chi, Yi etc) will use this power to open and strengthen one's joints, tendons and total body structure, so that, as Yi style Grandmaster Wang XiangZhai (王薌齋）: to be ready for the intensity of actual combat (please note: ready for combat, not yet able to win in combat!). And there are practitioners of Hard-chi-kung (氣硬功) fond of demonstrating breaking a sharply-pointed pole with the weakest part of his throat! And of course, for religious people, like part of a speedy training course for a Bodhisattva, as mentioned by his Holiness the Dalai Lama.
Nowadays, most people come to learn chi-kung are for various health-related reasons. For these people, I offer my advice as below:
1. Whatever type of chi-kung you are learning, make sure that you also learn how to manage the chi (just in case [congratulations!] one day you might encounter a massive in-flow of chi).
2. Honest to yourself in terms of your true reason for practicing chi-kung (Is it for strengthening your body recovering from a severe illness? Is it for mind-body tune-up as for general maintenance? Is it for martial art work-out? Is it for calming your mind so that you can have better EQ? Is it for old age infirmity?), and then organize your practice accordingly. Remember, this is primarily your responsibility rather than your teacher (sifu)'s responsibility.
And for those who are seeking spiritual enlightenment, I would suggest combing your pursue with studying the religious or spiritual classic texts.
And for those, for whatever reason, who are simply interested into everything and anything, and in particular like to challenge themselves into understanding "how powerful man's life force (or energy) is", I would say: Beware!