When the somnambulic state becomes more intense, the voluntary muscles of the limbs are excited into action; the somnambulist rises; dresses himself; and in pursuing his dream-imagery, wanders about, or sits down steadily to execute some task, which, however difficult in his waking hours, he now accomplishes with facility. The condition of the body in a physiological point of view becomes now a solemn mystery: the eyes are open, but insensible to light; the portals of the ears, also, but the report of a pistol will, in some cases, not rouse the sense of hearing; the sense of smell, too, is frequently strangely altered, and that of taste, likewise becomes perverted, or, perhaps, entirely suspended. The sensibility of the surface of the body is often remarkably impaired; and, for the time, partially or entirely abolished. In the case of a female somnambulist described in "The Philosophy of Natural History," by Dr. Smellie, he tells us that, when she was in one of her paroxysms, he ran a pin repeatedly into her arm—but not a muscle moved, nor was any symptom of pain discoverable. Here we may observe an important and interesting fact, that, as a general principle, in proportion as the mind concentrates its powers and energizes itself within, the sensibility of the body diminishes. The soldier, in his excitement on the battle-field, feels not his wounds; he will faint from loss of blood before he knows that he has been "hit." The unconsciousness of danger is often the best protection against it. On looking down a precipice, a sense of apprehension instantly suggests itself; the nervous system recoils; the circulation of the blood within the brain on a sudden becomes irregular; dizziness ensues and a total loss of command over the voluntary muscles. Man is probably the only being in whom this occurs; the stag, the goat, the antelope, will gaze unmoved down the chasms of the deepest Alpine precipices. The dizziness which is felt on ascending an elevation, arises undoubtedly from mental alarm, which modifies the impressions received by the eye, which no longer correctly estimates the relations of distance. Accordingly we are told by Mr. Wilkinson in his "Tour to the British Mountains," that a blind man, who was the scientific and philosophic Mr. Gough, ascended with him to the summit of one of the Cumberland Mountains; and in walking along, he described to him the fearful precipices which he pretended surrounded him; but soon he repented his inventive picturesque description, for the blind man, mentally affected by the supposed peril of his situation, became suddenly dizzy, and screaming with the apprehension that he was tumbling down the rocks into the abyss below, fell upon the ground. In cases of sleep-walking upon dangerous heights, there is no apprehension or fear—the mind is intently absorbed in the object pursued; all the muscular movements are performed with confidence and with unerring precision; and under these circumstances the gravitation of the body is supported on the most slender basis.
One of the most curious and indeed inexplicable phenomena connected with somnambulism is, that persons in this condition are said to derive a knowledge of surrounding objects independent of the organs of the external senses. The Archbishop of Bordeaux attested the case of a young ecclesiastic, who was in the habit of getting up during the night in a state of somnambulism, taking pen, ink, and paper, and composing and writing sermons. When he had finished one page he would read aloud what he had written, and correct it. In order to ascertain whether the somnambulist made use of his eyes, the archbishop held a piece of pasteboard under his chin to prevent his seeing the paper upon which he was writing; but he continued to write on, without being in the least incommoded. He also, in this state, copied out pieces of music, and when it happened that the words were written in too large a character, and did not stand over the corresponding notes, he perceived his error, blotted them out, and wrote them over again with great exactness. A somnambulist is mentioned by Gassendi, who used to dress himself in his sleep, go down into the cellar, draw wine from a cask, in perfect darkness—but if he awoke in the cellar, he had then a difficulty in groping his way through the passages back to his bed-room. The state of the eyes during somnambulism is found to vary considerably—they are sometimes closed—sometimes half closed—and frequently quite open; the pupil is sometimes widely dilated, sometimes contracted, sometimes natural, and for the most part insensible to light. This, however, is not always the case. The servant girl, whose case was so well described by Dr. Dyce, of Aberdeen, when this state was impending felt drowsy—a pain in the head, usually slight, but on one occasion very intense, then succeeded—and afterward a cloudiness or mistiness came over her eyes. Occasionally her sensations were highly acute; the eyelids appeared shut, though not entirely closed; the pupils were much contracted, and there was great intolerance of light. She could not name objects when the light of the candle or fire shone fully on them, but pointed them out correctly in the shade, or when they were dimly illuminated. At other times, however, the pupil of the eye was quite insensible to light. Her feelings also appear to have been very excitable. During one of her paroxysms she was taken to church; attended to the service with every appearance of devotion, and was at one time so much affected by the sermon, that she shed tears. The sensibility of the eye was also observed, in the case of Dr. Bilden; when a degree of light, so slight as not to affect the experimenter, was directed to the lids of this somnambulist, it caused a shock equal to that of electricity, and induced him to exclaim, "Why do you wish to shoot me in the eyes?" These are exceptions; as a general rule, the eye during somnambulism is insensible, and the pupil will not contract, though the most vivid flash of light be directed upon it. It also should be observed that although somnambulists will light a candle, it does not follow that they are guided by its light, or that they really see any thing by it. Their movements may still be purely automatic. This curious circumstance is finely illustrated by Shakspeare, who describes the Lady Macbeth walking in her sleep with a lighted taper in her hand:
"Gentlewoman.—Lo, yon, here she comes: This is her very guise, and upon my life, fast asleep.
Doctor.—How came she by that light?
Gentlewoman.—Why, it stood by her. She has light by her continually—'tis her command.
Doctor.—You see her eyes are open—
Gentlewoman.—Ay—but their sense is shut."
It is related of Negretti, a sleep-walker, that he would sometimes carry about with him a candle as if to give him light in his employment; but, on a bottle being substituted, he took it and carried it, fancying that it was a candle. Castelli, another somnambulist, was found by Dr. Soames translating Italian into French, and looking out the words in his dictionary. His candle being purposely extinguished, he immediately began groping about, as if in the dark, and although other candles were in the room, he did not resume his occupation until he had relighted his candle at the fire. In this case we may observe that he could not see, excepting with the candle he had himself lighted, and he was insensible to every other, excepting that on which his attention was fixed.
How are these curious anomalies to be explained? There is, it appears to us, a striking analogy between the actions as they are performed by the blind and those executed by somnambulists, who are insensible to light; the exaltation of the sense of touch, in blindness, is so great, that some physiologists have conceived the existence of a sixth sense—the muscular sense—which communicates the impression before the actual contact of objects. This muscular sense is supposed by Dr. Fowler to adjust the voice, the eye, and the ear, to the distances at which sounds are to be heard, and objects seen. It may, perhaps, be described as a peculiar exaltation of the sense of feeling. A lady during her somnambulism, observed to Despine, her physician, "You think that I do not know what is passing around me; but you are mistaken. I see nothing; but I feel something that makes an impression on me, which I can not explain." Another somnambulist, a patient of Hufeland, used to say invariably, "I feel"—"I am conscious" of the existence of this or that object. The blind girl, Jane Sullivan, described by Dr. Fowler, could, without a guide, feel her way to every part of the work-house, and recognize all its inmates by the feel of their hands and clothes. It is said of Laura Bridgman, that she could, in walking through a passage, with her hands spread before her, recognize her companions, and could in this way distinguish even their different degrees of intellect; nay, that she would regard with contempt a new-comer, after discovering her weakness of mind. It has been also observed, that the pupils in the Manchester Asylum for the Blind are aware, by this muscular sense, of their approach, even to a lamp-post, before actually coming against or up to it. May not the somnambulist walking through intricate passages and performing complicated manual operations in the dark, have his movements guided by this sense? May he not, in like manner, be sensible of his approach to obstructing obstacles, and may not this sense, in a higher degree of development, lead to perceptions, which are ordinarily conveyed to the mind through their appropriate and respective organs?
The sense of hearing in somnambulism is not often suspended, for, generally speaking, somnambulists will answer questions and carry on conversation; but it is remarkable that the same ear which may be deaf to the loudest noises, will perceive even a whisper from one particular person with whom the sleeper may alone appear to hold communion. In the "Transactions of the Medical Society" at Breslau, we meet with the case of a somnambulist who did not hear even the report of a pistol fired close to him. In another instance, that of Signor Augustin, an Italian nobleman, his servants could not arouse him from his sleep by any description of noise—even blowing a trumpet in his ear. On the other hand, the same individual would, in another paroxysm, apply his ear to the key-hole of the door, and listen attentively to noises which he heard in the kitchen. The sense of smell, as we have observed, is frequently altered. Brimstone and phosphorus are said to have a pleasant scent to the somnambulist, but sometimes it appears completely abolished. In one case, a snuff-box filled with coffee, was given to a somnambulist, who took it as he would have taken snuff, without perceiving the difference. So also is it with taste. Some somnambulists have not been able to distinguish wine from water.