Somnambulism occupies a pivotal position in the depth-psychological corpus, functioning simultaneously as a clinical phenomenon, a theoretical lever, and a window onto the dissociative architecture of the psyche. Pierre Janet, whose sustained clinical analysis in The Major Symptoms of Hysteria (1907) constitutes the most sustained treatment in the corpus, treats somnambulism not as a curiosity of neurological pathology but as the fundamental unit of hysterical organization: a state in which a fixed idea or system of affect achieves autonomous, dramatized enactment while the remainder of consciousness is excluded. Janet distinguishes monoideic from polyideic somnambulisms, traces their transformation into fugues and double personalities, and insists on their cardinal features — amnesia, repetition-compulsion, narrowed consciousness, and the paradox of rich behavioral expression alongside radical imperviousness to the external world. Jung, approaching the phenomenon from the side of its historical genealogy, situates somnambulism within the mesmeric tradition as 'magnetic sleep,' thereby locating it at the origin of hypnosis and suggestion theory. Abraham reads the somnambulistic dream-state as the nocturnal substrate from which hysterical attacks and twilight states derive. Across these voices, somnambulism serves as the paradigm case for understanding how consciousness can be simultaneously occupied and evacuated — a structure that underpins the depth-psychological concept of dissociation itself.
In contrast with the brilliant unfolding of some phenomena, we discover with amazement strange mental blanks. The same patient who looks as if he had very precise sensations... this same patient seems unable to grasp anything else.
Janet defines the structural paradox of somnambulism — vivid, coordinated enactment of one idea coexisting with total impermeability to all other stimuli — as its diagnostic signature.
, The Major Symptoms of Hysteria, 1907thesis
If we wish to understand hysteria well, it is very important we should know the possible transformations of that fundamental state of somnambulism.
Janet posits somnambulism as the foundational state from which all hysterical phenomena — fugues, double personalities, automatisms — derive through systematic transformation.
, The Major Symptoms of Hysteria, 1907thesis
In order to understand that degradation, that transformation of monoideic somnambulism into the hysterical fugue, we must study states of mind which are in some manner intermediate... polyideic somnambulisms.
Janet maps a developmental continuum from monoideic through polyideic somnambulism to fugue, establishing somnambulism as the generative matrix of complex dissociative states.
, The Major Symptoms of Hysteria, 1907thesis
This half-sleep was also called 'magnetic sleep' or somnambulism. People in these states were wholly under the will of the magnetist, they were 'magnetized' by him.
Jung locates somnambulism historically within the tradition of animal magnetism, identifying it as the predecessor concept to modern hypnosis and tracing its genealogy to Mesmer's experiments.
, Collected Works Volume 18: The Symbolic Life, 1976thesis
If you insist a great deal, if you remind her of facts characteristic of the agony, the subject will lose her composure, be agitated, and cease to hear us or see surrounding objects... the somnambulism has begun again.
Janet demonstrates that somnambulism is precipitated by ideational triggers, confirming its compulsive, automatic character and its immunity to voluntary interruption.
, The Major Symptoms of Hysteria, 1907thesis
One of the characteristics of these somnambulisms is that they repeat themselves indefinitely. Not only the different attacks are always exa[ct replicas]
Janet identifies compulsive, exact repetition as a defining law of somnambulism, distinguishing it from ordinary dreaming and linking it to the automatism of fixed ideas.
, The Major Symptoms of Hysteria, 1907thesis
This retrograde amnesia accompanying somnambulism is well brought into evidence... When awakened, she knows nothing about all this, and when you speak to her of what she said, she pretends that in her life there is no event in which any part was played by thieves, by a fire, or by Lucien.
Janet documents retrograde amnesia as an essential accompaniment of somnambulism, showing that the causative traumatic memories are inaccessible to waking consciousness.
, The Major Symptoms of Hysteria, 1907supporting
Out of the dream proceeds the somnambulistic dream in which the neurotic converts his phantasies into more or less complicated actions of which later he has no remembrance.
Abraham situates somnambulism on a continuum from ordinary dreaming through hypnoid states to hysterical attacks, emphasizing its amnestic aftermath and its conversion of unconscious fantasy into enacted behavior.
, Selected Papers on Psychoanalysis, 1927supporting
In polyideic somnambulisms and in fugues, it is upon this more serious feeling that the dissociation has borne. It is a feeling in its entirety, a more or less precise feeling that has separated from general consciousness.
Janet argues that polyideic somnambulism and fugues involve the dissociation of an entire affective complex — not merely a single idea — from general consciousness, complicating the monoideic model.
, The Major Symptoms of Hysteria, 1907supporting
You see that the four characteristic laws of somnambulisms apply to such cases... it seems still more justifiable to bring the two phenomena together and say that, upon the whole, f[ugues are degraded somnambulisms].
Janet enumerates the four laws governing somnambulism and demonstrates their applicability to fugue states, consolidating the theoretical unity of the two phenomena.
, The Major Symptoms of Hysteria, 1907supporting
Complete somnambulism was evidently characterized by a great number of intelligent manifestations; the subject expressed his idea, his dream, by his adjusted movements, which usually are to our mind the expression of reasonable thoughts.
Janet contrasts complete somnambulism — characterized by intelligent, purposive expression — with convulsive attacks, arguing that the latter are imperfect or degraded somnambulisms.
, The Major Symptoms of Hysteria, 1907supporting
The positive and negative phenomena in somnambulism with amnesia, in agitations with paralyses and anesthesias.
Janet systematizes the symptom structure of somnambulism in terms of the interplay between positive phenomena (enactment, agitation) and negative phenomena (amnesia, anesthesia, paralysis).
, The Major Symptoms of Hysteria, 1907supporting
Mollie Fancher... above all presented all the forms of somnambulism, from the simplest to the most complicated ones. There are in her at least five persons, who have very poetical pet names.
Janet uses the Fancher case to illustrate how the proliferation of somnambulistic states can generate distinct sub-personalities, each with its own memory and character.
, The Major Symptoms of Hysteria, 1907supporting
Their eyes seem open, but they are shut to all [external reality]. Our modern examples are much less dramatic, but they may be compared as to their most striking features.
Janet invokes Lady Macbeth's somnambulism as a literary anticipation of the clinical phenomenon, establishing its cultural recognizability and its defining feature of functional blindness to the external world.
, The Major Symptoms of Hysteria, 1907supporting
Catalepsy, form of somnambulism called, 33.
In the index, Janet classifies catalepsy as a form of somnambulism, extending the concept to cover states of waxy rigidity alongside the more active ambulatory presentations.
, The Major Symptoms of Hysteria, 1907aside
You will be able, after the crisis of sleep, to find again the recollection of it in states of artificially provoked somnambulism, about which I shall tell you a few words at the end of this lesson.
Janet notes that artificially induced somnambulism can serve as a diagnostic and mnemonic tool, recovering memories of hysterical crises inaccessible to ordinary waking consciousness.
, The Major Symptoms of Hysteria, 1907aside
We notice many mental phenomena at their beginning exactly as at the beginning of somnambulisms.
Janet draws a structural analogy between the onset of hysterical tics and the onset of somnambulism, suggesting a shared psychogenetic mechanism rooted in fixed traumatic impressions.
, The Major Symptoms of Hysteria, 1907aside