理工類輔導資料：閱讀理解Making Light

　　All we have a clock located inside our brains. Similar to your bedside alarm clock， your internal clock2 runs on a 24-hour cycle. This cycle，called a circadian rhythm，helps control when you wake，when you eat and when you sleep.

　　Somewhere around puberty，something happens in the timing of the biological clock. The clock pushes forward，so adolescents and teenagers are unable to fall asleep as early as they used to. When your mother tells you its time for bed，your body may be pushing you to stay up3 for several hours more. And the light coming from your computer screen or TV could be pushing you to stay up even later.

　　This shift4 is natural for teenagers. But staying up very late and sleeping late can get your bodys clock out of sync with the cycle of light and dark5. It can also make it hard to get out of bed in the morning and may bring other problems，too. Teenagers are put in a kind of a gray cloud6 when they dont get enough sleep，says Mary Carskadon，a sleep researcher at Brown University in Providence，RI7 .It affects their mood and their ability to think and learn.

　　But just like your alarm clock，your internal clock can be reset. In fact，it automatically resets itself every day. How? By using the light it gets through your eyes.

　　Scientists have known for a long time that the light of day and the dark of night play important roles in setting our internal clocks. For years，researchers thought that the signals that synchronize the bodys clock8 were handled through the same pathways that we use to see.

　　But recent discoveries show that the human eye has two separate light-sensing systems. One system allows us to see. The second system tells our body whether its day or night.

　　詞匯：

　　circadian adj. 晝夜節奏的，生理節奏的

　　adolescent n.青少年；adj.青少年的

　　puberty n.發育；青春期

　　sync n. (口語)同步；和諧，協調

　　synchronize V.(使)同時發生；(使)同步

　　注釋：

　　1.make light of ：輕視，不在乎。例如： We should not make light of their achievements.我們不應當低估他們的成就。

　　2. your internal clock ：指的是第一句中的a clock located inside our brains ，也即是第二段第一句中的the biological clock (生物鐘)。

　　3. stay up：不睡覺，熬夜

　　4. This shift：這種調整。指上文所描述的由于生理時間的變化青少年上床時間越來越晚的現象。

　　5. get your bodys clock out of sync with the cycle of light and dark ：打亂了你的生物鐘與晝夜時間循環之間的平衡

　　6. gray cloud ：提不起精神的狀態

　　7. Brown University in Providence， RI：位于美國羅得島州普羅維登斯的布朗大學。RI是Rhode Island(羅得島)的首字母縮寫；Providence 是羅得島州的首府。布朗大學是美國一流大學，

　　創建于1764 年，是世界聞名的美國"常春藤聯盟"(還包括哈佛大學、耶魯大學、普林斯頓大學、布朗大學、哥倫比亞大學、賓夕法尼亞大學、達特茅斯大學和康奈爾大學)中的一員。

　　8. the signals that synchronize the bodys clock：平衡生物鐘的光信號