我們的身體夜晚需要休息，白天需要清醒。大多數(shù)人每晚需要8到8.5個小時的睡眠才能正常運轉(zhuǎn)。找到更多的時間、更好的睡眠方法可能是個挑戰(zhàn)�？茖W(xué)家已經(jīng)確認了80多種不同的睡眠紊亂癥(sleep disorders)。有些睡眠紊亂癥是遺傳的。但是，許多睡眠紊亂癥是由于熬夜，經(jīng)�？鐣r區(qū)旅行以及上夜班而引起的。

　　參考譯文：

　　Our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives.Finding ways to get more and better sleep can be a challenge. Scientists have identified more than 80 different sleep disorders. Some sleeping disorders are genetic. But many problems are caused by staying up late and by traveling frequently between time zone or by working nights.