语法填空
Enough sleep is important to health. The amount of sleep ______(need) depends on the age of the person and the conditions in ______ sleep takes place. The young may need more sleep than _____ old, but usually eight hours are enough for the health of grown-ups. Some can do with _____ than this amount,____ ___ others may need more. Every person knows his own need. _____ is then a matter of good judgment to satisfy his need. Sleep should always be enough to make one bring back his ______ (strong) and get ready for a day’s work.
Fresh air is necessary to sound sleep. So it is not ______ reason for some people to think that it is practicable to sleep in the open air. A bath at bedtime, ________ hot nor cool but of body temperature, may be helpful to sleep. Sleep-producing drug should never be taken except when ______ (suggest) by a doctor.