Enough sleep is important to health． The amount of sleep21depends on the age of the per-son and the conditions in which sleep22． The young may need more sleep than the old， but generally eight hours are enough for the health of grown-ups． Some can23with less than this amount but24may need more． Every person knows his own need． It is then a matter of how to25it． Sleep should always be enough to make one relaxed（ 松弛） and ready for26work．
Fresh air is27to sound sleep（酣睡）． It is not without reason for some people to28that it is practical to sleep in the open air．29a person can keep himself warm， out-of-door sleeping probably gives the body30complete relaxation．
Ability to sleep is largely a habit． The conditions referred to only lead to sleep． Out-of-door31， a good habit of regular drinking and the avoidance of late eating and32are all helpful to sound sleep． Such factors are largely within the control of any person． A bath at33， neither hot nor cold but of34temperature， may be helpful to sleep． Sleeping pills should never be taken except when suggested by35，
A young woman in a small German town was going to give a piano concert． Her posters said that she was a pupil of Franz Liszt， the great Hungarian pianist． This was not true． One day the woman learned that Li
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