托福閱讀材料：人體腦白金

褪黑素與我們的睡眠質量密切相關，下面的新托�？荚囬喿x資料要討論的就是褪黑素有助睡眠的原因。

Melatonin, sometimes called “the hormone of darkness,” plays an important role in regulating our daily sleep patterns. This hormone is produced by our bodies and in most organisms melatonin production is higher during the night than during the day.
　　褪黑素，又名黑素細胞凝集素的荷爾蒙，在調節(jié)我們日常睡眠規(guī)律中扮演重要角色。人體自身分泌褪黑激素，而且大多數生物夜晚比白天分泌得更多。

In addition to their body’s own melatonin, many people take melatonin supplements in an attempt to help them sleep, fight jet lag or balance out seasonal affective disorder.
　　此外，一些人通過體外補充褪黑素改善睡眠，緩解飛機時差感、平衡季節(jié)性情緒失調。

Melatonin And Memories
　　褪黑素對記憶的影響

But a study by a group of scientists at the University of Houston suggests that melatonin might have a negative impact on the ability to form new memories.
　　但是，休斯頓大學的科學家們研究表明：褪黑素阻礙記憶形成。

The researchers were interested in how the body’s internal clock affects the formation of new memories. They found that small striped minnows called zebra fish learned very well during the day but very poorly at night, when melatonin levels are higher.
　　研究人員想弄清楚體內生物鐘如何影響新生記憶的形成。研究人員發(fā)現斑馬魚白天學習能力很好;夜晚卻很差，而夜晚褪黑素分泌旺盛。

They wondered if melatonin played a role in learning and memory.
　　研究人員懷疑褪黑素影響學習和記憶。

Melatonin And Learning
　　褪黑素對學習的影響

They treated zebra fish with extra melatonin during the day, boosting the hormone levels to night-time amounts.
　　白天，研究人員喂給斑馬魚褪黑素，促進斑馬魚夜晚褪黑素分泌。

They discovered that high melatonin did not affect learning per se, but dramatically reduced the fishes’ ability to form new memories, or to remember what they’d learned.
　　研究人員發(fā)現大量的褪黑素沒有直接影響學習本身，但是卻很大程度地使斑馬魚的記憶衰退，斑馬魚不記得學過的東西。

Then the scientists inhibited melatonin activity in the fish. They did this by blocking melatonin receptors with inhibitory drugs. The fishs’ melatonin levels were unchanged, but the ability of melatonin to affect the brain was blocked.
　　接著，科學家們抑制斑馬魚體內的褪黑素的作用：抑制藥物阻礙褪黑素受體。斑馬魚褪黑素分泌量沒改變，但是褪黑素不能再影響大腦。

Blocking Melatonin
　　阻礙褪黑素

With melatonin activity blocked, the ability of the fish to form new memories was drastically improved, even at night.
　　褪黑素的作用受阻，斑馬魚新生記憶能力明顯改善，夜晚也很好。

This research has potential benefits for humans. For example, the use of melatonin receptor blockers could improve performance of night-time cognitive tasks, helping people such as night-shift workers or students cramming for exams.
　　該項研究帶給人類潛在好處。例如，褪黑素受體的阻礙能影響人夜晚的認知能力，那么對于那些夜班工作者和熬夜備考的學生都有所幫助。