SLEEP 165 



open and appears to be awake. In this state he is 

 peculiarly open to suggestion by words, which can be 

 made to set up the most extraordinary illusions and 

 consequent behaviour. On " waking " the patient has no 

 memory of what has occurred, though a suggestion 

 received in the somnambulic stage may persist in the un- 

 conscious memory, and cause conduct on the part of the 

 patient (many hours after the brief hypnotic sleep has 

 passed) which is entirely inexplicable by the patient 

 himself or by those who are not aware of the fact that he 

 had received a " suggestion " or " direction " when in the 

 hypnotised state. The senses of smell, hearing, and touch 

 are often abnormally acute in a hypnotised patient, but 

 there is no evidence to show that the brain of such a person 

 can be influenced or " communicated with " excepting 

 through the ordinary channels of the sense-organs. " Day- 

 dreaming " and " reverie " are conditions resembling the 

 hypnotic sleep. The brain of each of us is constantly 

 doing much of its work in a state of partial hypnotism, 

 and the term " unconscious cerebration " has been used 

 to describe it. A most interesting and difficult chapter 

 of the study of mental disease belongs here. 



The prolonged sleep of some animals in the winter, 

 called " hibernation," seems to be closely similar to 

 ordinary sleep, but is set up by the depressing action 

 of continuous cold instead of by the daily recurring 

 quiescence of night and by the exhaustion due to the 

 day's activity. Many animals such as the marmot 

 and dormouse, the frog and the snail exhibit this 

 winter sleep. It has been found by experiment that even 

 in midsummer the dormouse can be made to " hibernate," 

 by exposing it artificially to a low temperature, and 

 hibernating animals can be roused from their long sleep 

 by bringing them into warmth. During the winter 

 sleep hibernating animals take no food, the pulse is 



