Regressive hypnosis is certainly one of the most "suggestive" and fascinating methods of investigating consciousness, in fact more and more people are asking for it, preferring this to other more demanding and long approaches.
What can be investigated? The most general answer is "the contents removed from memory", but in the collective imagination these removed contents can relate to any area of life, from the precious object placed somewhere, to the name of a person lost from sight for many years, up to get to the identity we had in a previous existence.
Needless to say, this last theme is the one that tickles the curiosity of most people, sometimes motivated by a real problem, unresolved in today's life, sometimes driven by the desire to verify and control hypotheses and expectations already mentally formulated .
Depending on the field of reference, the intent expressed by the operator and the expectations of those undergoing the experience should be distinguished between hypnosis used as a suggestive "play" or "show" technique and therapeutic hypnosis.
The information that emerged could be of various kinds, presumably not too impactful in the life of the individual and easily sustainable from an emotional point of view. It is not necessary for the operator to be a therapist, but being a delicate practice, however, it would be good to use caution and delicacy anyway, since sometimes even the apparently more banal suggestion can trigger unexpected reactions.
When regressive hypnosis is used instead for therapeutic purposes, for example to understand the origin of a problem, the emotional contents can be particularly intense and more painstakingly elaborated on a conscious level, that's why, in these cases, despite the Italian legislation does not impose it, it would be good to turn to a psychotherapist (psychologist or doctor) specialized in hypnotic psychotherapy.
Contrary to what is normally thought, it is not a predisposition of the personality to make a subject hypnotizable or not, because the mind can be "educated" to this special way of concentrating, but the particularity of therapeutic regression through hypnosis implies that there is an involvement of the most profound conscience structures, which, to protect the subject himself, could prevent certain past experiences from emerging, if emotionally too strong.
There is therefore a sort of "lifesaver", which disconnects the connection when the tension becomes excessive and in this case it would not be wise to insist. When instead the consciousness manages to evoke the past, can we be sure that what emerges is true? Unfortunately not.
What emerges in hypnosis is the subjective experience of an experience, not the absolute truth, but only a point of view, that of the subject, re-elaborated by his own personality. This is why a memory surfaced during a hypnotic trance could not be used as a test in court .
On the other hand from the therapeutic point of view it is not important that the truth of the memory emerge, because what made us suffer from our past is mainly the way in which we lived it, the meaning we have attributed to it, regardless of how the facts really took place, and it is precisely on this that the therapeutic path deals: having the possibility of changing point of view and finding, today, another way of reacting, possibly more constructive, to similar situations, tracing new meanings and new solutions.
And the previous lives? Since the absolute, objective truth is not traceable in a past explored with regressive hypnosis, the possibility of reliving episodes of previous lives cannot be scientifically demonstrated. However, it often happens that people report places never seen before and situations set in another era: it cannot even be shown that this is not true.
Perhaps searching now, in the present time, for the same places and meticulously checking whether certain people really existed, conclusions could be drawn, but this is not the task of hypnotic psychotherapy.