Sleep walking or night wandering, known also by its Latin name of noctambulism, is a well-known phenomenon. Somnambulism is not so good a term for it, since that signifies too many things. In sleep walking a person rises from his bed in the night, apparently asleep, walks around with closed or half opened eyes, but without perceiving anything, yet performs all sorts of apparently purposeful and often quite complicated actions and gives correct answers to questions, without afterward the least knowledge of what he has said or done. If this all happens at the very time and under the influence of the full moon, it is spoken of as moon walking or being moonstruck.

Under the influence of this heavenly body the moonstruck individual is actually enticed from his bed, often gazes fixedly at the moon, stands at the window or climbs out of it, “with the surefootedness of the sleep walker,” climbs up upon the roof and walks about there or, without stumbling, goes into the open. In short, he carries out all sorts of complex actions. Only it would be dangerous to call the wanderer by name, for then he would not only waken where he was, but he would collapse frequently and fall headlong with fright if he found himself on a height.

Besides there is absolute amnesia succeeding this. Upon persistent questioning there is an attempt to fill in the gaps in memory by confabulation, like the effort to explain posthypnotic action. Furthermore, it is asserted that a specially deep sleep always ushers in night wandering, that indeed the latter in general is only possible in this condition. It is more frequent with children up to puberty and throughout that period than with adults. At the same time the first outbreak of sleep walking occurs often at the first appearance of sexual maturity. According to a widespread folk belief sleep walking will cease in a girl when she becomes pregnant with her first child.

It seems to me that practically no scientific treatment of this problem exists. Modern psychiatry, so far as it takes a sort of general notice of it, contents itself, as Krafft-Ebing does, with calling night wandering “a nervous disease,” “apparently a symptomatic manifestation of other neuroses, epilepsy, hysteria, status nervosus.”[2] The older literature is more explicit. It produces not only a full casuistic but seeks to give some explanation aside from a reference to neurology.[3] So, for example, the safety in climbing upon dangerous places finds this explanation, that the sleep walker goes there with closed eyes and in this way does not see the danger, knows no giddiness and above all is in possession of a specially keen muscular sense.

The phenomena of sleep walking and moon walking must be acknowledged, as far as I can see, almost entirely as pathological yet connected or identical with analogous manifestations of normal profound sleep. The dreams in such sleep, in contrast with those of light sleep, are characterized by movements. These often amount merely to speaking out, laughing, weeping, smacking, throwing oneself about and so on, or occasionally to complicated actions, which begin with leaving the bed. Further comparison shows the night wandering as symptomatically similar to hysterical and hypnotic somnambulism. This interpretation might be objected to upon the ground that unfortunately we know nothing of the origin of the motor phenomena of the dream and that understanding of the hysterical and hypnotic somnambulism is deplorably lacking. Still less has science to say about the influence of the moon upon night wandering. The authors extricate themselves from the difficulty by simply denying its influence. They bring forward as their chief argument for this that many sleep walkers are subject to their attacks as frequently in dark as in moonlight nights and when sleeping in rooms into which no beam of moonlight can penetrate. Spitta indeed explains it thus: “The much discussed and romantically treated ‘moon walking’ is a legend which stands in contradiction to hitherto observed facts. That the phantasy of the German folk mind drew to itself the pale ghostly light of the moon and could reckon from it all sorts of wonderful things, proves nothing to us.” I can only say here that ten negative cases signify nothing in the face of a single positive one and a thousand-fold experience undoubtedly represents a certain connection between the light of the full moon and the most complicated forms of sleep walking.

Not merely does science avoid these things on account of their strangeness, but also the poets best informed in the things of the soul, whom the problems of night wandering and moon walking should stimulate. From the entire province of artistic literature I can mention only Shakespeare's “Macbeth,” Kleist's “Prinz von Homburg,” the novel “Maria” by Otto Ludwig, “Das SÜndkind” by Anzengruber, “JÖrn Uhl” by Gustav Frenssen and “AebelÖ” by Sophus Michaelis.[4] Finally Ludwig Ganghofer has briefly sketched his own sleep walking in his autobiographical “Lebenslauf eines Optimisten,” and Ludwig Tieck has given unrestrained expression to his passionate love toward this heavenly body in different portions of his works.

Only in “Maria” and in “AebelÖ” however do these themes play an important part, while in the other works mentioned they serve properly only as adornment and episodic ornament. I am not able to explain this unusual restraint, unless we accept the fact that our best poets shrink from touching upon questions which they themselves can so little understand.

It has been expected that the psychoanalytic method, which casts such light upon the unconscious, might do much to advance the understanding of the problems of sleep walking and moon walking. But unfortunately no one undergoes such an expensive and time-consuming treatment as psychoanalysis for moon walking, so that the hoped for illumination can come at the best only as a by-product in the psychoanalysis of neurotics. That has in fact been my good fortune twice, where I have been able to lift the curtain, though only a little, in two cases among my patients and also in individuals who were otherwise healthy. What I discovered there, I will relate in detail in what follows.

One point of view I will first set forth. Two questions appear to me to stand out among those closely bound with our theme. First on the motor side. Why does not the sleep walker, who is enjoying apparently a specially deep slumber, sleep on quietly and work out the complexes of his unconscious somehow in a dream, even though with speech or movement there? Why instead is he urged forth and driven to wander about and engage in all sorts of complicated acts? It is one of the most important functions of the dream to prolong sleep quietly. And then in the second place, What value and significance must be attributed to the moon and its light? These two chief questions must be answered by any theory that would do justice to the question of sleep walking and moon walking.