题目内容：

阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式．

Should naps（小睡） actually1.    （take） during the day？ Well， we certainly know from2.（evident） in the sleep center and that of many other scientists that naps can give you benefits for both your brain3.  your body． But naps can actually be4.double﹣edged sword because while we're awake during the day， we're building up sleepiness or sleep pressure． So when you try to fall asleep at night， you'll fall asleep quickly and then you'll stay asleep． And when we sleep， we actually release that sleepiness so that we wake up the next morning feeling5.（refresh）．

So if you take a nap during the day， especially if you take it too late in the afternoon， you will actually release some of that sleepiness and it will make it much6.（hard） to fall asleep and stay asleep soundly throughout the night． So the advice would be if you don't struggle with your sleep and you can nap7.（regular）， then naps are just fine．

But if you do find it difficult8. （fall） asleep or stay asleep at night， then you should avoid naps and try to build up that healthy sleepiness in the evening．

The ideal nap depends on9.  you want from that nap． Different stages of sleep actually give you different types of brain and body10. （benefit）．