听力文摘：午休的学问

When you go back to work or class after lunch, why is it so hard to stay awake?

当我们用完午餐回去工作或上课时，为什么很难保持清醒呢？

Although we get energy from food, we also use lots of energy to digest it.

尽管我们从食物中获取能量，但也需要耗费许多能量来消化这些食物。

Your energy use increases 25-50% as you digest a meal.

消化一餐就会增加百分之二十五至五十的能量消耗。

With all that action going on in the digestive system, the body sends extra blood to the gut¹ to supply oxygen and other necessities.

有了消化系统内的一系列活动，身体才能源源不断地将额外的血液输送到消化道以提供充足的氧气和其它必需物。

As food enters the stomach, the intestines³ secrete⁴ substances that dilate⁵, or expand, the blood vessels⁶ that supply them with blood.

当食物进入胃，肠道便分泌许多物质，它们使得为肠道供血的血管膨胀或扩张。

As a result, more blood flows to the upper digestive tract,and there's a bit less to go around to the rest of the body.

结果便是更多的血液流向上消化道，而循环于身体其它部分的血液则相应减少，

That might make your arms and legsand brain feel a little sluggish⁷!

这时你可能感觉浑身懒洋洋的，连大脑也变得迟钝起来。

At the same time, the small intestine² releases a hormone⁸ that activates⁹ the part of the brain that controls sleep, making you drowsy¹⁰.

同时，小肠释放出一种荷尔蒙，它可以激活控制睡眠的大脑区域，让你昏昏欲睡。

Finally, the natural components¹¹ in foods can also contribute tothe snooze effect. Certain foods, especially carbohydrates¹², increase production of serotonin in the brain.

最后，食物中的天然成分也会让你打盹。某些食物，特别是碳水化合物，会增加大脑中血清素的生成。

Serotonin works both to stop sugar craving¹³, and to make you very relaxed.

血清素既可以抑制吃甜食的欲望，又可让你倍感放松。

The larger the meal, the more pronounced that feeling can be.

吃得越多，这种感觉就越明显。

With all of these physiological¹⁴ reasons why wemight feel sleepy after eating, a siesta¹⁵ after lunch sounds like a brilliant idea, and maybe after dinner and breakfast too!

鉴于诸多生理原因导致我们餐后昏昏欲睡，也许午餐抑或早晚餐后小憩一会儿是个明智的选择。

1 gut   

n.[pl.]胆量；内脏；adj.本能的；vt.取出内脏

参考例句：

• It is not always necessary to gut the fish prior to freezing.冷冻鱼之前并不总是需要先把内脏掏空。
• My immediate gut feeling was to refuse.我本能的直接反应是拒绝。

2 intestine   

adj.内部的；国内的；n.肠

参考例句：

• This vitamin is absorbed through the walls of the small intestine.这种维生素通过小肠壁被吸收。
• The service productivity is the function,including external efficiency,intestine efficiency and capacity efficiency.服务业的生产率是一个包含有外部效率、内部效率和能力效率的函数。

3 intestines   

n.肠( intestine的名词复数 )

参考例句：

• Perhaps the most serious problems occur in the stomach and intestines. 最严重的问题或许出现在胃和肠里。 来自辞典例句
• The traps of carnivorous plants function a little like the stomachs and small intestines of animals. 食肉植物的捕蝇器起着动物的胃和小肠的作用。 来自辞典例句

4 secrete   

vt.分泌；隐匿，使隐秘

参考例句：

• The pores of your body secrete sweat.身上的毛孔分泌汗液。
• Squirrels secrete a supply of nuts for winter.松鼠为准备过冬而藏坚果。

5 dilate   

vt.使膨胀，使扩大

参考例句：

• At night,the pupils dilate to allow in more light.到了晚上，瞳孔就会扩大以接收更多光线。
• Exercise dilates blood vessels on the surface of the brain.运动会使大脑表层的血管扩张。

6 vessels   

n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人

参考例句：

• The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
• All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》

7 sluggish   

adj.懒惰的，迟钝的，无精打采的

参考例句：

• This humid heat makes you feel rather sluggish.这种湿热的天气使人感到懒洋洋的。
• Circulation is much more sluggish in the feet than in the hands.脚部的循环比手部的循环缓慢得多。

8 hormone   

n.荷尔蒙，激素，内分泌

参考例句：

• Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
• This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。

9 activates   

使活动，起动，触发( activate的第三人称单数 )

参考例句：

• Activates the window and displays it in its current size and position. 激活窗口，保持当前的大小及位置不变。
• Pulling out the alarm switch activates alarm and pushing it deactivates it. 闹钟的开和关是通过拔出和按入闹铃开关实现的。

10 drowsy   

adj.昏昏欲睡的，令人发困的

参考例句：

• Exhaust fumes made him drowsy and brought on a headache.废气把他熏得昏昏沉沉，还引起了头疼。
• I feel drowsy after lunch every day.每天午饭后我就想睡觉。

11 components   

（机器、设备等的）构成要素，零件，成分； 成分( component的名词复数 )； [物理化学]组分； [数学]分量； （混合物的）组成部分

参考例句：

• the components of a machine 机器部件
• Our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。

12 carbohydrates   

n.碳水化合物，糖类( carbohydrate的名词复数 )；淀粉质或糖类食物

参考例句：

• The plant uses the carbohydrates to make cellulose. 植物用碳水化合物制造纤维素。 来自《简明英汉词典》
• All carbohydrates originate from plants. 所有的碳水化合物均来自植物。 来自辞典例句

13 craving   

n.渴望,热望

参考例句：

• a craving for chocolate 非常想吃巧克力
• She skipped normal meals to satisfy her craving for chocolate and crisps. 她不吃正餐，以便满足自己吃巧克力和炸薯片的渴望。

14 physiological   

adj.生理学的，生理学上的

参考例句：

• He bought a physiological book.他买了一本生理学方面的书。
• Every individual has a physiological requirement for each nutrient.每个人对每种营养成分都有一种生理上的需要。

15 siesta   

n.午睡

参考例句：

• Lots of people were taking a short siesta in the shade.午后很多人在阴凉处小睡。
• He had acquired the knack of snatching his siesta in the most unfavourable circumstance.他学会了在最喧闹的场合下抓紧时间睡觉的诀窍。