Late-Night Drinking

      Coffee lovers beware. Having a quick “pick-me-up” cup of coffee¹ late in the day will play havoc with² your sleep. As well as being a stimulant, caffeine interrupts the flow of melatonin, the brain hormone that sends people into a sleep.
　　Melatonin levels normally start to rise about two hours before bedtime. Levels then peak between 2 am and 4 am, before falling again³. “It’s the neurohormone that controls our sleep and tells our body when to sleep and when to wake,” says Maurice Ohayon of the Stanford Sleep Epidemiology Research Center at Stanford University in California. But researchers in Israel have found that caffcinated coffee halves the body’s levels of this sleep hormone.

Lotan Shilo and a team at the Sapir Medical Center in Tel Aviv University found that six volunteers slept less well after a cup of caffeinated coffee than after drinking the same amount of decaf. On average, subjects slept 336 minutes per night after drinking caffeinated coffee, compared with 415 minutes after decaf. They also took half an hour to drop off⁴ - twice as long as usual - and jigged around⁵ in bed twice as much.
　　In the second phase of the experiment, the researchers woke the volunteers every three hours and asked them to give a urine sample, Shilo measured concentrations of a breakdown product of melatonin. The results suggest that melatonin concentrations in caffeine drinkers were half those in decaf drinkers. In a paper accepted for publication in Sleep Medicine, the researchers suggest⁶ that caffeine blocks production of the enzyme that drives melatonin production.
　　Because it can take many hours to eliminate caffeine from the body, Ohayon recommends that coffee lovers switch to decaf after lunch.

词汇:

beware / bɪ"weə(r) /v.当心:小心     

enzyme / "enzaɪm /n.酶

caffeinated adj.含咖啡因的；加入咖啡因的    

caffeine / ˈkæfɪi:n/n.咖啡因

stimulant / ˈstɪmjʊlənt /n.兴奋剂    

melatonin / ˌmelə"təʊnɪn /n.退黑激素

halve / hɑ:v /v.二等分；减半    

hormone / "hɔ:məʊn /n.荷尔蒙，激素

decaf n.脱咖啡因咖啡   

neurohormone n. 神经激素

urine / ˈjʊrɪn /n.尿

注释:

1. have a quick “pick-me-up” cup of coffee:喝一杯快速提神的咖啡。pick-me-up意为“提神饮料”，这里用作定语。2. play havoc with:干扰；……造成严重破坏。例如: The noise of engines can play terrible havoc with a driver’snerves.发动机的嘈杂噪声能严重扰乱驾驶员的神经。

3. Levels then peak between 2 am and 4 am, before falling again:褪黑激素的浓度在凌晨2点和4点之间达到最高值，然后再次下降。before在此处可以译为“然后”。

4. drop off:睡着。例如: He dropped off in the armchair.他在扶手椅上睡着了。

5. jig around:辗转反侧。jig意为“急动，蹦蹦跳跳”。例如: Stop jigging about, Billy, and just stand still for a moment.别到处乱蹦，比利，稳稳地站一会儿。

Which of the following tells us how caffeine affects sleep?

A:Caffeine blocks production of the enzyme that stops melatonin production. B:Caffeine interrupts the flow of the hormone that prevents people from sleeping. C:Caffeine halves the body’s levels of sleep hormone. D:Caffeine stays in the body for many hours.

Sleep Lets Brain File Memories¹

　　To sleep. Perchance to file?² Findings published online this week by the Proceedings³ of the National Academy of Sciences further support the theory that the brain organizes and stows memories formed during the day while the rest of the body is catching zzz"s⁴.
　　Gyorgy Buzsaki of Rutgers University⁵ and his colleagues analyzed the brain waves of sleeping rats and mice. Specifically, they examined the electrical activity emanating from⁶ the somatosensory neocortex⁷ (an area that processes sensory information) and the hippocampus⁸, which is a center for learning and memory. The scientists found that oscillations in brain waves from the two regions appear to be intertwined. So-called sleep spindles (bursts of activity from the neocortex) were followed tens of milliseconds⁹ later by beats in the hippocampus known as ripples. The team posits that this interplay between the two brain regions is a key step in memory consolidation. A second study, also published online this week by the Proceedings of the National Academy of Sciences, links age-associated memory decline¹⁰ to high glucose levels.
　　Previous research had shown that individuals with diabetes suffer from increased memory problems. In the new work, Antonio Convit of New York University School of Medicine and his collaborators studied 30 people whose average age was 69 to investigate whether sugar levels, which tend to increase with age, affect memory in healthy people as well. The scientists administered¹¹ recall tests, brain scans and glucose tolerance tests, which measure how quickly sugar is absorbed from the blood by the body"s tissues. Subjects with the poorest memory recollection, the team discovered, also displayed the poorest glucose tolerance. In addition, their brain scans showed more hippocampus shrinkage than those of subjects better able to absorb blood sugar.

　　"Our study suggests that this impairment¹² may contribute to the memory deficits¹³ that occur as people age." Convit says. "And it raises the intriguing possibility that improving glucose tolerance could reverse some age-associated problems in cognition.¹⁴" Exercise and weight control can help keep glucose levels in check¹⁵, so there may be one more reason to go to the gym.

词汇：

perchance / pə:ˈtʃɑ:ns / adv. 偶然；可能

online adj.& adv. 在线的(地)
stow v. 储存，堆装

emanate / "eməneɪt /  v. 发源 (from)
somatosensory / ˌsəʊ,mətə’sen-sərɪ /  adj.体觉的

neocortex / ˌni:əʊˈkɔ:teks /   n. 新（大脑）皮层
oscillation / ˌɒsɪˈleɪʃn /  n. 振荡

intertwine / ˌɪntə"twaɪn /  v.  (使)缠绕，(使)缠结
spindle / "spɪndl /  n. 纺锤体

ripple / "rɪpl /  n. 波动，脉动
diabetes /ˌdaɪəˈbi:tis,-i:z /   n. 糖尿病

recollection / ˌrekəˈlekʃən /  n. 回忆,（常作-s） 回忆起的事物
shrinkage / ˈʃrɪŋkɪdʒ /  n.  收缩 减少

impairment n. 损伤
intrigue / ɪn"tri:ɡ/  v. 引起……兴趣（或好奇心）

cognition / kɒgˈnɪʃən /  n. 认识，认识的结果

注释：

Which of the following statements is nearest in meaning to the sentence "To sleep. Perchance to file?"?

A:Does brain arrange memories in useful order during sleep? B:Does brain have memories when one is sleeping? C:Does brain remember files after one falls asleep? D:Does brain work on files in sleep?

Late-night Drinking

    Coffee lovers beware. Having a quick “pick-me-up” cup of coffee¹ late in the day will play havoc with² your sleep. As well as being a stimulant, caffeine interrupts the flow of melatonin, the brain hormone that sends people into a sleep.

    Melatonin levels normally start to rise about two hours before bedtime. Levels then peak between 2 am and 4 am, before falling again.³"It"s the neurohormone that controls our sleep and tells our body when to sleep and when to wake，，，says Maurice Ohayon of the Stanford Sleep Epidemiology Research Center at Stanford University in California. But researchers in Israelhave found that caffeinated coffee halves the body"s levels of this sleep hormone.

    Lotan Shilo and a team at the Sapir Medical Center in Tel Aviv University found that six volunteers slept less well after a cup of caffeinated coffee than after drinking the same amount of decaf. On average, subjects slept 336 minutes per night after drinking caffeinated coffee, compared with 415 minutes after decaf. They also took half an hour to drop off⁴一 twice as long as usual 一 and jigged around⁵ in bed twice as much.

    In the second phase of the experiment, the researchers woke the volunteers every three hours and asked them to give a urine sample. Shilo measured concentrations of a breakdown product of melatonin. The results suggest that melatonin concentrations in caffeine drinkers were half those in decaf drinkers. In a paper accepted for publication in Sleep Medicine，the researchers suggest⁶ that caffeine blocks production of the enzyme that drives melatonin production.

    Because it can take many hours to eliminate caffeine from the body，Ohayon recommends that coffee lovers switch to decaf after lunch.

词汇：

beware /bɪ"weə/ vi.当心；小心

stimulant/"stɪmjʊl(ə)nt/ n.兴奋剂

caffeine/"kæfiːn/ n.咖啡因

melatonin/,melə"təʊnɪn/ n.褪黑激素

hormone/"hɔːməʊn/ n.荷尔蒙,激素

neurohormone /,nʊro"hɔrmon; ,njʊro"hɔrmon/ n,神经激素

caffeinated /"kæfiəneitid/ adj.含咖啡因的;加入咖啡因的

halve /hɑːv/ vt. 二等分;减半

decaf/"diːkæf/ n.脱咖啡因咖啡

urine /"jʊərɪn; -raɪn/ n.尿

enzyme /"enzaɪm/ n. 酶

注释：

1. have a quick "pick-me-up" cup of coffee:喝一杯快速提神的咖啡。pick-me-up 意为“提神饮料”，这里用做定语。

2.  play havoc with:干扰；对        造成严重破坏。例如：The noise of engines can play terrible havoc with a driver"s nerves.发动机的嘈杂声能严重扰乱驾驶员的神经。

3. Levels then peak between 2 am and 4 am, before falling again.褪黑激素的浓度在凌晨2 点和 4点之间达到最高值，然后再次下降。before在此处可以译为“然后”。

4.  drop off:睡着。例如:He dropped off in the armchair.他在扶手椅上睡着了。

5.  jig around:辗转反侧。jig:急动，蹦蹦跳跳。例如:Stop jigging about, Billy, and just stand still for a moment.别到处乱蹦，比利，稳稳地站一会儿。

6.  suggest:在这里不作“建议”解，它的意思是“间接地表明；暗示”。例如:I’m not suggesting that the accident was your fault.我并不是说那事故是你的错。

Which of the following tells us how caffeine affects sleep?

A:Caffeine blocks production of the enzyme that stops melatonin production B:Caffeine interrupts the flow of the hormone that prevents people from sleeping C:Caffeine halves the body"s levels of sleep hormone D:Caffeine stays in the body for many hours

Sleep Lets Brain File Memories¹

    To sleep. Perchance to file?² Findings published online this week by the Proceedings³ of the National Academy of Sciences further support the theory that the brain organizes and stows memories formed during the day while the rest of the body is catching zzz"s⁴.
　　Gyorgy Buzsaki of Rutgers University⁵ and his colleagues analyzed the brain waves of sleeping rats and mice. Specifically, they examined the electrical activity emanating from⁶ the somatosensory neocortex⁷ (an area that processes sensory information) and the hippocampus⁸, which is a center for learning and memory. The scientists found that oscillations in brain waves from the two regions appear to be intertwined. So-called sleep spindles (bursts of activity from the neocortex) were followed tens of milliseconds⁹ later by beats in the hippocampus known as ripples. The team posits that this interplay between the two brain regions is a key step in memory consolidation.

A second study, also published online this week by the Proceedings of the National Academy of Sciences, links age-associated memory decline¹⁰ to high glucose levels.
　　Previous research had shown that individuals with diabetes suffer from increased memory problems. In the new work, Antonio Convit of New York University School of Medicine and his collaborators studied 30 people whose average age was 69 to investigate whether sugar levels, which tend to increase with age, affect memory in healthy people as well. The scientists administered¹¹ recall tests, brain scans and glucose tolerance tests, which measure how quickly sugar is absorbed from the blood by the body"s tissues. Subjects with the poorest memory recollection, the team discovered, also displayed the poorest glucose tolerance. In addition, their brain scans showed more hippocampus shrinkage than those of subjects better able to absorb blood sugar.
　　"Our study suggests that this impairment¹² may contribute to the memory deficits¹³ that occur as people age." Convit says. "And it raises the intriguing possibility that improving glucose tolerance could reverse some age-associated problems in cognition.¹⁴" Exercise and weight control can help keep glucose levels in check¹⁵, so there may be one more reason to go to the gym.

词汇：

perchance/ pə(:)ˈtʃɑ:ns/adv. 偶然；可能

online/ ˌɒnˈlaɪn/adj.&adv. 在线的
stow / stəʊ/v. 贮藏，堆装

emanate/ "eməneɪt/v. 发源
somatosensory / ˌsəʊmətəʊ"sensərɪ/adj.体觉的

neocortex / ˌniəuˈkɔ:teks/n. 新（大脑）皮质
oscillation / ˌɒsɪˈleɪʃn/n. 振荡

intertwine / ˌɪntə"twaɪn/v.  缠绕
spindle/ "spɪndl/n. 纺锤体

ripple / "rɪpl/n. 波动，脉动
diabetes/ ˌdaɪəˈbi:ti:z/n . 糖尿病

recollection / ˌrekəˈlekʃn/n. 回忆
shrinkage / ˈʃrɪŋkɪdʒ/n. 收缩

impairment/ ɪmˈpeəmənt/n. 损伤
intrigue  / ɪn"tri:ɡ/v.引起……兴趣（或好奇心）

cognition / kɒgˈnɪʃn/n. 认识

注释：

1. file memories：归档并储存记忆。 file：意为 "to put or keep (papers,etc. ) in useful order for storage or reference"（把…归档）。
2. To sleep. Perchance to file? ：从莎士比亚笔下哈姆雷特的独白中的名句" To sleep: perchance to dream. "改编而来。
3. the Proceedings: (科学文献、会议文献)汇编，常用复数形式。
4. zzz：（拟声词）打鼾声
5. Rutgers University：美国新泽西州立大学 (the State University of New Jersey)。
6. emanating from：发源于。
7. neocortex：新(大脑)皮质，尤指大的高等哺乳动物大脑中新生长的部分，也叫做 neopallium。neo-：前縀，意思是"新的"。
8. thehippocampus：大脑侧面脑室壁上的隆起物，也称"海马状突起"，在泛记过程中起主要作用。
9. tens of milliseconds：几十毫秒
10. age-associated memory decline：与年龄相关的记忆衰退
11. administer：实施
12. this impairment：指上句中 hippocampus shrinkage.
13. memory deficits：记忆衰退
14. … the intriguing possibility that improving glucose tolerance could reverse some age-associated problems in cognition：令人兴奋的可能性，即不断改善葡萄糖容许量可以完全改变对某些与年龄相关的认知问题。
15. keep glucose levels in check：限制葡萄糖水平。 in check：在控制中，被阻止。

Which of the following statements is nearest in meaning to the sentence "To sleep. Perchance to file?"?

A:Does brain arrange memories in useful order during sleep? B:Does brain have memories when one is sleeping? C:Does brain remember files after one falls asleep? D:Does brain work on files in sleep?

Sleeplessness

    Insomnia or sleeplessness is a common complaint¹ of women as they enter into menopause. Insomnia means having trouble falling asleep or staying asleep or the feeling that your sleep was not adequate for you. For women who are having night sweats, their sleep is broken by frequent awakening and therefore not refreshing. Generally once² the night sweats are controlled a normal sleep pattern returns. If it doesn"t it may be, or have become chronic insomnia.³ How do you know?⁴

    If you suffer from insomnia every night or most nights for a period of one month then you have chronic insomnia. If you"re not having night sweats then it"s time to look for other causes of sleeplessness. Depression and anxiety disorders are the most common causes of chronic insomnia. If you feel depressed you need to be checked by a qualified health care provider⁵. Movement disorders such as restless leg syndrome are second on the list⁶ of insomnia for them； there are new medicines that may help. Other common causes are shift working, and pain.

    In up to⁷ 30% of people with chronic insomnia no cause can be identified. Medical treatment of these people has generally been with sleeping pills. It is estimated that 25% of the adult population in Americatook some type of medicines for sleep last year. It is generally agreed that sleeping pills should only be in the lowest dose⁸ and for the shortest possible time.

    Sleep hygiene⁹ is directed at changing bad sleep habits. The recommendations are： 一 Go to bed only when sleepy. 一Do not wait up to a specified time. 一Avoid caffeine and alcohol in the evening, etc.

词汇：

insomnia /ɪn"sɒmnɪə/ n.失眠，失眠症

qualified /"kwɒlɪfaɪd/ adj.有资格的，胜任的，具备必要条件的

syndrome/"sɪndrəʊm/ n.综合病症，综合症状，

identify /aɪ"dentɪfaɪ/ vt.识别，鉴定

dose/dəʊs/ n.(药物等的)(一次)剂量，一剂，一服

hygiene/"haɪdʒiːn/ n.卫生，卫生学，保健学

recommendation /,rekəmen"deɪʃ(ə)n/ /n.劝告，建议；推荐

specify /"spesɪfaɪ/ vt.具体指定，明确说明

caffeine /"kæfiːn/ n.咖啡因，咖啡碱

complaint/kəm"pleint/ n.疾病；抱怨，诉苦

menopause/"menəpɔːz/ n.绝经，绝经期，更年期

refreshing/rɪ"freʃɪŋ/ adj.提神的，凉爽的，清凉的

chronic /"krɒnɪk/ adj.(疾病）慢性的

depression /dɪ"preʃ(ə)n/ 抑郁，沮丧，消沉

disorder /dɪs"ɔːdə/ n.（身，信机能的）紊乱，不适，病

注释：       

1.complaint:此处意为“疾病”。

2.once:—旦（引导时间状语从句）

3.If it doesn"t it may be, or have become chronic insomnia.如果正常的睡眠规律不能恢复，则可 能成为或已经成为慢性失眠了。If k doesn"t中的k指上一句提到的normal sleep pattern。

4. How do you know?是 How do you know if it may be or have become chronic insomnia?的省略。

5.a qualified health care provider：—个合格的保健工作者，这里泛指医生或健康咨询专家等。

6.second on the list:在名单上列第二，即从重要性来看位于第二。

7.up to:接近

8.in the lowest dose:用最小剂量

9.sleep hygiene:睡眠的卫生，指与睡眠有关的一系列健康习惯。

Which of thp following does not fit with sleep hygiene?

A:Making a rule to go to bed at a specific time every day B:Going to bed when sleepy, not always at the same time C:Trying not to drink any caffeine and alcohol in the evening D:Changing bad sleep habits and following doctors" advice

Sleeplessness

    Insomnia or sleeplessness is a common complaint¹ of women as they enter into menopause. Insomnia means having trouble falling asleep or staying asleep or the feeling that your sleep was not adequate for you. For women who are having night sweats, their sleep is broken by frequent awakening and therefore not refreshing. Generally once² the night sweats are controlled a normal sleep pattern returns. If it doesn"t it may be, or have become chronic insomnia.³ How do you know?⁴

    If you suffer from insomnia every night or most nights for a period of one month then you have chronic insomnia. If you"re not having night sweats then it"s time to look for other causes of sleeplessness. Depression and anxiety disorders are the most common causes of chronic insomnia. If you feel depressed you need to be checked by a qualified health care provider⁵. Movement disorders such as restless leg syndrome are second on the list⁶ of insomnia for them； there are new medicines that may help. Other common causes are shift working, and pain.

    In up to⁷ 30% of people with chronic insomnia no cause can be identified. Medical treatment of these people has generally been with sleeping pills. It is estimated that 25% of the adult population in Americatook some type of medicines for sleep last year. It is generally agreed that sleeping pills should only be in the lowest dose⁸ and for the shortest possible time.

    Sleep hygiene⁹ is directed at changing bad sleep habits. The recommendations are： 一 Go to bed only when sleepy. 一Do not wait up to a specified time. 一Avoid caffeine and alcohol in the evening, etc.

词汇：

insomnia /ɪn"sɒmnɪə/ n.失眠，失眠症

qualified /"kwɒlɪfaɪd/ adj.有资格的，胜任的，具备必要条件的

syndrome/"sɪndrəʊm/ n.综合病症，综合症状，

identify /aɪ"dentɪfaɪ/ vt.识别，鉴定

dose/dəʊs/ n.(药物等的)(一次)剂量，一剂，一服

hygiene/"haɪdʒiːn/ n.卫生，卫生学，保健学

recommendation /,rekəmen"deɪʃ(ə)n/ /n.劝告，建议；推荐

specify /"spesɪfaɪ/ vt.具体指定，明确说明

caffeine /"kæfiːn/ n.咖啡因，咖啡碱

complaint/kəm"pleint/ n.疾病；抱怨，诉苦

menopause/"menəpɔːz/ n.绝经，绝经期，更年期

refreshing/rɪ"freʃɪŋ/ adj.提神的，凉爽的，清凉的

chronic /"krɒnɪk/ adj.(疾病）慢性的

depression /dɪ"preʃ(ə)n/ 抑郁，沮丧，消沉

disorder /dɪs"ɔːdə/ n.（身，信机能的）紊乱，不适，病

注释：       

1.complaint:此处意为“疾病”。

2.once:—旦（引导时间状语从句）

3.If it doesn"t it may be, or have become chronic insomnia.如果正常的睡眠规律不能恢复，则可 能成为或已经成为慢性失眠了。If k doesn"t中的k指上一句提到的normal sleep pattern。

4. How do you know?是 How do you know if it may be or have become chronic insomnia?的省略。

5.a qualified health care provider：—个合格的保健工作者，这里泛指医生或健康咨询专家等。

6.second on the list:在名单上列第二，即从重要性来看位于第二。

7.up to:接近

8.in the lowest dose:用最小剂量

9.sleep hygiene:睡眠的卫生，指与睡眠有关的一系列健康习惯。

Which of thp following does not fit with sleep hygiene?

A:Making a rule to go to bed at a specific time every day B:Going to bed when sleepy, not always at the same time C:Trying not to drink any caffeine and alcohol in the evening D:Changing bad sleep habits and following doctors" advice

Late-night Drinking

    Coffee lovers beware. Having a quick “pick-me-up” cup of coffee¹ late in the day will play havoc with² your sleep. As well as being a stimulant, caffeine interrupts the flow of melatonin, the brain hormone that sends people into a sleep.

    Melatonin levels normally start to rise about two hours before bedtime. Levels then peak between 2 am and 4 am, before falling again.³"It"s the neurohormone that controls our sleep and tells our body when to sleep and when to wake，，，says Maurice Ohayon of the Stanford Sleep Epidemiology Research Center at Stanford University in California. But researchers in Israelhave found that caffeinated coffee halves the body"s levels of this sleep hormone.

    Lotan Shilo and a team at the Sapir Medical Center in Tel Aviv University found that six volunteers slept less well after a cup of caffeinated coffee than after drinking the same amount of decaf. On average, subjects slept 336 minutes per night after drinking caffeinated coffee, compared with 415 minutes after decaf. They also took half an hour to drop off⁴一 twice as long as usual 一 and jigged around⁵ in bed twice as much.

    In the second phase of the experiment, the researchers woke the volunteers every three hours and asked them to give a urine sample. Shilo measured concentrations of a breakdown product of melatonin. The results suggest that melatonin concentrations in caffeine drinkers were half those in decaf drinkers. In a paper accepted for publication in Sleep Medicine，the researchers suggest⁶ that caffeine blocks production of the enzyme that drives melatonin production.

    Because it can take many hours to eliminate caffeine from the body，Ohayon recommends that coffee lovers switch to decaf after lunch.

词汇：

beware /bɪ"weə/ vi.当心；小心

stimulant/"stɪmjʊl(ə)nt/ n.兴奋剂

caffeine/"kæfiːn/ n.咖啡因

melatonin/,melə"təʊnɪn/ n.褪黑激素

hormone/"hɔːməʊn/ n.荷尔蒙,激素

neurohormone /,nʊro"hɔrmon; ,njʊro"hɔrmon/ n,神经激素

caffeinated /"kæfiəneitid/ adj.含咖啡因的;加入咖啡因的

halve /hɑːv/ vt. 二等分;减半

decaf/"diːkæf/ n.脱咖啡因咖啡

urine /"jʊərɪn; -raɪn/ n.尿

enzyme /"enzaɪm/ n. 酶

注释：

1. have a quick "pick-me-up" cup of coffee:喝一杯快速提神的咖啡。pick-me-up 意为“提神饮料”，这里用做定语。

2.  play havoc with:干扰；对        造成严重破坏。例如：The noise of engines can play terrible havoc with a driver"s nerves.发动机的嘈杂声能严重扰乱驾驶员的神经。

3. Levels then peak between 2 am and 4 am, before falling again.褪黑激素的浓度在凌晨2 点和 4点之间达到最高值，然后再次下降。before在此处可以译为“然后”。

4.  drop off:睡着。例如:He dropped off in the armchair.他在扶手椅上睡着了。

5.  jig around:辗转反侧。jig:急动，蹦蹦跳跳。例如:Stop jigging about, Billy, and just stand still for a moment.别到处乱蹦，比利，稳稳地站一会儿。

6.  suggest:在这里不作“建议”解，它的意思是“间接地表明；暗示”。例如:I’m not suggesting that the accident was your fault.我并不是说那事故是你的错。

Which of the following tells us how caffeine affects sleep?

A:Caffeine blocks production of the enzyme that stops melatonin production B:Caffeine interrupts the flow of the hormone that prevents people from sleeping C:Caffeine halves the body"s levels of sleep hormone D:Caffeine stays in the body for many hours