SLEEP. 207 



who has a cheerful disposition and a sunny temper is not 

 only unlikely himself to suffer from nervous ailments, 

 but, by a contagious influence, helps to keep others well 

 and happy. 



4. Sleep, however, sound and plenty of it, is the one 

 great condition of nervous health. The use of sleep is to 

 give the cerebrum a period of complete rest, for growth 

 and repair. While awake, even when we are not doing 

 brain-work, the mind and cerebrum are in action all the 

 time; feeling and willing and thinking. Perhaps not 

 feeling much or willing much or thinking hard, but still 

 doing some or all of those things every moment. So long 

 as we are conscious, the mind and cerebrum are at work. 

 Healthy sound sleep is a state of the body in which the 

 cerebrum is entirely at rest and there is no conscious- 

 ness. A due amount of it is as absolutely necessary for 

 a healthy brain and mind, as periods of rest are for the 

 muscles or stomach. 



5. The Amount of Sleep Necessary for Health varies 

 with age and employment. Children need more sleep 

 than older persons, and those whose chief work is men- 

 tal, need more than those whose work is muscular. 



The brain of a child has to grow and develop and is 

 easily fatigued; it needs plenty of the deep thorough 

 rest given by sleep. Moreover the muscles of a healthy 

 boy or girl are full of life, and need abundant exercise. 

 This makes severe mental work dangerous (p. 57). The 

 organs which nourish the body, can only in a few 

 favored persons provide at the same time for the needs 



4. What is the use of sleep ? What is said concerning mind and 

 cerebrum during waking hours? What is healthy sound sleep? 



5. What persons need most sleep ? First reason why children need 

 more than adults? Another reason? What is fhe usual result of 



