Why Do People Sleepwalk?

1. When Mesmer first established hypnosis, he discovered that hypnotized individuals often exhibited symptoms of sleepwalking. According to modern classification criteria for hypnosis, sleepwalking is the deepest state that can be induced by hypnosis. If a hypnotist induces a subject into a sleepwalking state and commands them to perform everyday tasks, the subject can carry out those tasks just as well as in a normal waking state.

The principle of hypnosis involves creating a center of excitement in the central nervous system through verbal suggestions while inhibiting activity in other parts. Sleepwalking operates in a similar manner, where a portion of the central nervous system becomes aroused while other parts remain in a sleep state.

Brahnlu conducted a post-hypnotic suggestion experiment to demonstrate that post-hypnotic suggestions can make individuals experience vivid and realistic hallucinations. The experiment was as follows:

I hypnotized a clever, sensitive, but not hysterical woman and gave her a complex post-hypnotic suggestion, engaging all her senses. I suggested that she heard military music in the hospital courtyard, and soldiers coming up the stairs into the room...

A drunken musician came up, speaking nonsense and attempting to embrace her. She gave him two slaps and called for a nurse and the head nurse, who quickly arrived and drove the drunkard away. All these situations were conveyed to the hypnotized subject. As a result, when she woke up, she vividly experienced the scenes described above. She had never before experienced such hallucinations, and now she could not rid herself of them.

She looked around, asking other patients if they had witnessed everything that had just happened. She was unable to distinguish between reality and hallucination. When everything concluded, I told her, "It was all just a hallucination that I suggested to you." Only then did she believe that what she had witnessed was indeed a hallucination, but she insisted that it was almost as real as the actual experience, far more vivid than a dream.

After waking up from the hypnotic state, the patient forgot everything that had occurred during hypnosis. After some time, due to the effects of post-hypnotic suggestions, they experienced vivid hallucinations. This experiment provides an explanation for one pattern of sleepwalking: just like hypnotized subjects, sleepwalkers merely perform a rehearsed script in the form of a hallucination.

Of course, this explanation is only a rough metaphor.

2. Psychoanalytic Theory

Freud believed that sleepwalking is a manifestation of repressed emotions from the subconscious that emerge at the appropriate moment. Indeed, sleepwalkers often have distressing experiences. In fact, sleepwalking can be intuitively explained using psychoanalytic theory: when the forces of the id accumulate to a certain degree, they break through the vigilant ego's defenses.

Faced with the overwhelming power of the id, the vigilant ego can only escape and some vigilant egos are even captured to assist because one's actions are the responsibility of the ego. After the id has caused a bit of havoc and expended some energy, the vigilant ego immediately sends the id back into its cage. In order to avoid punishment from the superego, the vigilant ego keeps the hidden information secret, resulting in the sleepwalker having no knowledge of what just occurred upon waking up.

Although the above explanation may seem fantastical, it is logically sound.