HYGIENE OF THE NERVOUS SYSTEM 329 



to the arms and to the legs. Physical exercise redistributes 

 the blood and equalizes the circulation. Light exercise 

 should, therefore, follow hard study. The student before 

 retiring at night is greatly aided in getting to sleep and is 

 put in a better condition for the next day's work by ten to 

 fifteen minutes of light gymnastics. A daily walk of two 

 or three miles is also an excellent means of counteracting 

 the effects of mental work. The brain worker should, 

 however, avoid violent exercise or the carrying of any kind 

 of exercise to exhaustion. 



Sleep, and plenty of it, is one of the first requirements 

 of the nervous system. It is during sleep that the ex- 

 hausted brain cells are replenished. To shorten the time 

 for sleep is to weaken the brain and to lessen its working 

 force. No one should attempt to get along with less than 

 eight hours of sleep each day and most people require 

 more. Children require more sleep than adults. Those 

 under six years should have from eleven to twelve hours of 

 sleep per day. Children between six and ten years should 

 have at least ten hours. 



Insomnia, or sleeplessness, on account of its effects upon 

 the nefvous system, is to be regarded as a serious con- 

 dition, and hygienic means for relieving it should be 

 diligently sought. Having its cause in nervousness, a 

 disturbed circulation of the brain, or some form of nervous 

 exhaustion, it is benefited through relieving these condi- 

 tions and in the manner already described. Of course the 

 external conditions for aiding sleep should not be over- 

 looked. The bed should be comfortable, and the room 

 should be cool, well ventilated, dark, and quiet. The 

 inducing of sleep by means of drugs is a dangerous prac- 

 tice and should never be resorted to except under the 

 direction of the physician. 



