Synopsis
There are some good books out there written by Hypnotherapists such as Michael Newton and Delores Cannon who have documented stories from many people's unconscious mind. Both of these Hypnotherapists stumbled into Past Life Regression by asking a simple question while a subject was under hypnosis, but was not yielding the source of a physical problem: "Go back to the moment in time when this physical symptom first became apparent." From here a description of a past life emerged.

Article
If you believe that each of us is a being of light, energy, and consciousness who is having more than one human experience over vast expanses of "human" time, you have an opportunity to explore your greater Self through hypnosis.

This method of reaching a trance state is sometimes likened to a meditative state. Unlike most self meditation, a hypnotist guides the subject first into a relaxed state, where the body can appear as if it is sleeping, yet the unconscious mind remains very focused and alert.

Once a person has reached a level where the conscious mind is quieted, the mental doorway is opened to a vast storehouse of information. Our three-dimensional belief system can be stretched by contacting our Higher Self from this deep level of hypnosis.

Hypnosis can be used to regress a person to one or more lifetimes. This has proven effective in alleviating strong, yet seemingly out-of-place feelings or physical symptoms that have no "present-time" reason for being there. For example, A subject might come to a hypnotherapist with a complaint of a deep pain near a kidney. After ruling out any physical issues from a medical professional, the patient can be referred to a hypnotherapist.

In a past life regression the subject might relay a scene of a battle being fought with swords and bows & arrows. In this scene the subject may see them self as being run through the torso with a blade; hence dying a violent, painful death. This past-life physical injury and traumatic death may have stayed with the person from one life to the next, manifesting as a "physical memory" and pain in the current life.

It is the task for the hypnotherapist to help the subject disassociate from that past-life memory; to leave it in the past and start living in the present free of that pain.

Regressing to a "time" between lifetimes can allow a subject to identify the purpose for being on the Earth in this lifetime as Michael Newton wrote about in his books. Some refer to this as Spiritual Hypnotherapy.

Hypnosis is a valuable tool for getting in touch with our Higher Self through our unconscious (or subconscious) mind. But be ready to leave your per-conceived beliefs behind.