Irma

托福閱讀 練習小短文 - 退黑激素 (生物學科) 

退黑激素 Melatonin 就內容而言不難理解，主要就是退黑激素的有效功用如輔助睡眠、調整時差以及與人體記憶能力相關等等，目前在美國屬於保健食品類型，因此相關報導其實不難找到。所以其實由此可知，其實托福閱讀的素材其實非常多，主要就是對於主要國外的報章雜誌的理解程度是否達到母語者理解程度，因此加強閱讀能力不外乎就是多閱讀並且檢討來提升。

Melatonin And Memories

     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.

　　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.

　　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.

　　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.

　　They wondered if melatonin played a role in learning and memory.

　　Melatonin And Learning

　　They treated zebra fish with extra melatonin during the day, boosting the hormone levels to night-time amounts.

　　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.

　　Then the scientists inhibited melatonin activity in the fish. They did this by blocking melatonin receptors with inhibitory drugs. The fish’s melatonin levels were unchanged, but the ability of melatonin to affect the brain was blocked.

　　　　Blocking Melatonin

　　With melatonin activity blocked, the ability of the fish to form new memories was drastically improved, even at night.

　　　　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.

      In the study, 116 people spent five days in room where the amount of light and sleep was controlled. They were awake for 16 hours and asleep for eight hours each day.

     Initially the patients were exposed to 16 hours of room light during their waking hours. They were then moved onto eight hours of room light in the morning and eight hours of dim light in the evening.

    The researchers found that electrical light between dusk and bedtime strongly suppressed melatonin levels. With dim light, melatonin was produced for 90 minutes more a day.

    Dr Joshua Gooley, lead author from Brigham and Women's Hospital and Harvard Medical School, said: "Our study shows that this exposure to indoor light has a strong suppressive effect on the hormone melatonin.

  "This could, in turn, have effects on sleep quality and the body's ability to regulate body temperature, blood pressure and glucose levels."

   Keeping the lights on through the night also reduced the amount of melatonin produced.

   Dr Gooley said: "Given that chronic light suppression of melatonin has been hypothesised to increase relative risk for some types of cancer and that melatonin receptor genes have been linked to type 2 diabetes, our findings could have important health implications for shift workers."