17.Enough sleep is important to health.The amount of sleep (41)needed(need) depends on the age of the person and the conditions in (42)whichsleep takes place.The young may need more sleep than (43)theold,but usually eight hours is enough for the health of grown-ups.Some can do with (44)lessthan this amount,but others may need more.Every person knows his own need.(45)Itis then a matter of good judgment to satisfy his need.Sleep should always be enough to make one bring back his (46)strength(strong) and get ready for a day's work.
Fresh air is necessary to sound sleep.So it is not (47)without reason for some people to think that it is practicable to sleep in the open air.A bath at bedtime,(48)neither hot nor cool but of body temperature,may be helpful (49)to sleep.The sleep-producing drug should never be taken except when(50)suggested(suggest) by a doctor.