Consequently, the purport of dreams, as well as the way they originate, is alike in sleep and hypnosis. But, as in sleep we believe ourselves in another situation, and encounter all sorts of sense-delusions, so is it in hypnosis. And as a subject in hypnoses can be replaced in earlier periods of his life, so in dreams also. Many habitually dream that they are again undergoing the final examination at college many years after. Complete changes of personality also take place in dreams. An officer who greatly admired Hannibal, told me that he had dreamed he was Hannibal and had fought an imaginary battle in that character. Another man was even less modest; he once dreamed he was God and was ruling the world.

We cannot decide whether there is more dreaming in hypnosis than in sleep, because we can never know with certainty how many dreams happen in sleep. While some say that dreams only occur during a short period of sleep, others, like Kant, Forel, Exner, and Simonin, go so far as to deny that there is any sleep without dreaming; they say that dreaming is continuous, but that most dreams are forgotten. Jouffroy, also, considers that we invariably dream when asleep. Bigelow does not think that dreaming has been proved to be continuous, but he is convinced that the mental activity is as unbroken in sleep as it is in the waking state. Vaschide, with whom Nacke agrees, likewise thinks that sleep without dreaming hardly ever occurs.

In spite of all this, we can find a difference between the phenomena of deep hypnosis and of sleep in several points - (i) in the apparently logical connection between the suggested idea and the hypnotic subject's own thoughts; (2) in the movements of the subject, and particularly in his speech, since there may be a conversation between the experimenter and his subject.

With regard to the first point, we have seen (p. 133 et seq.) that a series of ideas sometimes links itself logically to another particular idea. Consequently, the difference between hypnosis and sleep is not a fundamental one. Even if this . linking is, on the whole, merely mechanical and the result of habitual association of ideas, it must be admitted that the power of discrimination is not entirely in abeyance in hypnosis, but can, as we have seen, display a certain amount of activity. Still, the whole connection can be broken at any moment by suggestion, as I have shown; in the same way the whole current of ideas may change at any moment. It appears, at once from this, that the independence of a hypnotic subject is very limited. The logical connection mentioned above lasts only as long as the experimenter permits. In the dreams of the night, which Radestock refers entirely to the pause in logical thought, there is not usually such a logical connection, because it but rarely happens that they centre in a definite idea as in hypnotic suggestion. In hypnosis the attention of the hypnotic subject is directed to the experimenter; the ideas given by the latter are accepted, and retain a certain amount of supremacy.

In sleep the most diverse sensations are conducted to the brain; as the sleeper's attention is not usually directed to a special point, it is much less easy for a definite idea to gain supremacy. Giessler points out how easily a dreamer's personality can be changed. When a change of character in hypnosis is brought about by suggestion, the subject does his utmost to play the part suggested; on the other hand, as Giessler again points out, a person who is merely dreaming immediately transfers the experiences, characteristics, titles, functions, and occupations of others to his own dream ego, and without effort. I will not go into details of examples. It is known that Voltaire wrote poetry in sleep, that mathematicians sometimes solve problems when asleep, and that the celebrated physiologist, Burdach, worked out many scientific ideas in sleep. It is said of Agassiz that he solved the problem of fossil fish which he was engaged upon, in a night-dream (Bigelow). Hack Tuke reports that the utterances of a person who is dreaming that he is disputing with some one are not invariably illogical; and he relates that one night, after having taken part in a lively discussion on spiritualism, he had a dream in which he worked out a series of experiments with considerable acumen.

I mentioned the movements in hypnosis as a further contrast between this state and sleep; but this assuredly forms no qualitative distinction, since it is known that people move in sleep. The activity of the muscles in sleep is often an automatic continuation of movements begun awake. This happens, e.g., with people who fall asleep in making one particular movement; they continue the- movement in sleep. For example, coachmen will go on driving, and riders will hold the bridle without falling off. Birds fall asleep standing, and aquatic birds go through the motions of swimming slowly with one foot when asleep, which shows that a group of voluntary muscles can be in a constant state of activity. In all these cases the muscular action is very like the contractions and continuous movements described on p. 77. Moreover, Henle has pointed out in his Lectures on Anthropology that muscular action is almost invariably present in sleep. Physiologists term this activity tonus; it enables a sleeper to assume and maintain a position which could not be controlled without muscular action.

Slipping down in bed is a symptom of extreme exhaustion in typhoid fever.

Besides this, external stimuli may cause movements during sleep. It must not be assumed that they happen apart from mental activity. If part of a sleeper's body is uncovered, he will draw the cover over it; if he is tickled, he will scratch the place. Even if these are regarded as physical reflexes without any accompanying mental action, which is not proved, the case is essentially different from the movements which children make in sleep, at command. If a child is told to turn over, it will do so without waking. This is an act which, as Ewald remarks, may be fairly compared with the phenomena of hypnosis, in which movements of the same kind, if greater in extent, are made at command.