We all know that a good night's rest helps us stay healthy． After we sleep for 7 or 8 hours in bed and （1） 　　up next morning， our mind is better prepared to memorize and learn something．

But what about getting a rest during the middle of the day？

Scientists say， "Short periods of sleep， napping（小睡）， may help learning and memory． Napping

can help young children learn better． It can （2） 　　help older people remember longer．"

Take China as an example． Chinese people are used to napping after lunch．

Recently researchers made a survey among nearly 3， 000 Chinese people over 65 years old． The researchers asked them （3） 　　they napped and for how long． They found that about 60 percent of them took a nap and they napped for 60 to 90 minutes． The research shows that napping for about an hour is the best．

However， these are the findings for those （4） 　　the age of 65． Doctors say that napping for about an hour may be too （5） 　　for young and healthy people． And they believe that half an hour is enough to （6） 　　young and healthy people from feeling tired． By doing so， （7） 　　will help them stay awake．

Doctors also say， "If you have trouble falling asleep at （8） 　　， take a daytime nap for less than 45 minutes and don't nap after 3 p． m． in the afternoon．"