Hypnotherapy has its roots in Hypnotism practiced widely in Ancient Egypt and Greece, in Sleep Temples, where ritual, music and chanting provided a background for peaceful reflection. Much later in the 18th century the work of Franz Mesmer led investigators to examine the basis for his extraordinary popularity.  They concluded that although Mesmer claimed that supernatural forces were at work ("Animal magnetism"), all his results could be explained by the power of "Imagination and belief". His contemporaries Puysegur and Abbe de Faria proposed that the power of the hypnotist was less important than the state of "Lucid Sleep" which subjects entered; a state which we now recognise as "Trance". This state together with other phenomena associated with hypnotic states such as time distortion was found by Bernheim to be producable in the vast majority of a normal population. 

Entering the more modern era of psychotherapy and psychology, Janet suggested that hypnotism dissociated the conscious mind and behaviour from the subconscious mind, thereby allowing therapists to communicate directly with the client's subconscious. Coue was a proponent of modern hypnotherapy practices noting the power of self-hypnosis and auto-suggestion, in self development and strengthening self esteem.

During this period of growth in the understanding of the importance of the subconscious mind the pioneer Psychoanalysts Freud and Jung steered interest away from hypnotherapy to prolonged "Talking" therapies. This predominance of talking psychotherapy continued through the work of Adler and Mazlo, influencing Rogers who developed the core principles of humanistic approaches to clients in therapy. Perls also became a pioneer proponent of Gestalt therapy within the humanistic/existential movement.

Milton Erickson emerged from this era as a pioneer in hypnotherapy practice from a background in psychiatry and family therapy. His conviction that the client's subconscious is equipped to find solutions, but requires strategic help from the therapist to achieve this, differentiated his approach from the pure existential therapists. He believed in utilising everything that the client brought to the consultation, which led him to use unusual and innovative approaches and language, with extensive use of metaphor. His methods are embraced by a large number of therapists today. The work of Erickson, together with Virginia Satir and Fritz Perls were studied and "Modelled" to form the basis of Neuro-Linguistic Programming (NLP) which has a major part in hypnotherapy practice today, as well as in life-coaching and professional-coaching.