咖啡一之道.

I love coffee.

我愛喝咖啡。

The intoxicating nutty aroma.

令人上癮般的堅果香氣。

The rich chocolatey taste.

厚實的巧克力口感。

Some days I drink three cups like the average American I am.

有時候我一天喝三杯咖啡，跟一般的美國人一樣。

Other days, I drink more like five or six.

有些時候我會喝到五或六杯。

But is that too much?

這樣會太多嗎？

First the good news.

我們先從好消息談起。

It"s almost impossible to overdose on coffee.

咖啡幾乎不可能攝取過量。

There is a lethal dose of caffeine but it"s somewhere around 10 grams and the average cup of Joe has around 100 milligrams.

咖啡因攝取達一定程度確實會致命，但你得喝到 10 克；我們一般喝的咖啡一杯只有 100 毫克。

You"d likely have to drink 100 cups in rapid succession to OD.

你大概得喝上 100 杯才算超量。

But that"s not to say there"s no such thing as too much.

不過這並不代表你可以想喝幾杯就喝幾杯。

The FDA recommends no more than four to five cups a day for the average healthy adult.

根據美國食品藥品監督管理局 (FDA) 建議，普通健康成年人一天不要超過四或五杯。

More than that and you might start to experience some nasty side effects.

超過該建議量，可能會開始出現不好的副作用。

- Most people take in coffee to increase their focus and concentration

多數人喝咖啡是為了提高注意力、專註程度。

but once you take in too much you start to lose that focus

一旦喝太多，你反而會流失注意力。

People start getting more agitated, irritable.

人們會變得躁動不安、易怒。

Narrator: That"s thanks to the hormone, adrenaline.

這是因為腎上腺素這種荷爾蒙所導致的。

When caffeine hits your system it stimulates your adrenal glands which release the hormone into your body.

當咖啡因開始生效，它會刺激腎上腺體，將荷爾蒙釋放至體內，

It makes you feel energetic and alert.

讓你充滿活力、提高警覺。

Perfect for a fight or flight situation.

當你遇上「或戰或逃」的緊急狀況會很有幫助。

But too much can be a bad thing.

但太多就變成壞事。

Especially if you suffer from anxiety.

尤其如果你本身就有焦慮問題。

- But with anxiety you also wanna be careful not to overstimulate or trigger any sort of panic attacks and make anxiety worse,

談到焦慮癥狀，要小心不能過度刺激，不能誘發任何型態的恐慌感，讓焦慮症惡化；

which certainly too much caffeine can do.

而太多咖啡因絕對會造成這種情況。

- Adrenaline from caffeine can also increase your heart rate.

咖啡因激起的腎上腺素也可能使心跳加速。

That"s why doctors also recommend against drinking coffee if your heart sometimes beats irregularly.

這也就是為什麼如果有心跳不規律的問題，醫生會建議不要喝咖啡。

But the risk is really only for bonafide coffee junkies.

然而這樣的風險只針對真正的咖啡上癮者。

According to at least two observational studies you have to drink at least nine cups of coffee a day to put yourself at risk of arrhythmia.

根據至少兩項觀察研究，你一天得喝超過九杯咖啡才可能害自己心律不整。

And finally, there"s the question of sleep.

最後還必須考慮到睡眠。

Coffee"s enemy.

咖啡對睡眠很不利。

Caffeine launches a double threat on your slumber.

咖啡因對你的睡眠會產生雙重威脅。

It blocks the neurochemical adenosine which is what tells your brain that you"re tired.

神經化學方面，咖啡因會抑製腺苷；當你疲累時腺苷會傳訊給大腦。

It releases a cocktail of stimulants into your brain.

咖啡因會釋放出混合刺激物給大腦，

Adrenaline, dopamine, and glutamate.

包含腎上腺素、多巴胺、谷氨酸。

So after donning your sixth cup of coffee,

因此六杯咖啡下肚以後，

you don"t just feel awake but full of energy.

你不但十分清醒，而且活力滿滿。

It will power you through that 2:30 meeting or the last class of the day.

它能帶你撐過下午兩點半的會議，或者熬過最後一節課。

But if you overdo it, the effect won"t wear off when it"s time for bed.

可是當你喝太多，咖啡因的效果會拖到上床時間還沒效退。

In one study, researchers monitored the sleep of a dozen volunteers.

在一項研究中，研究者監控了 12 位自願者的睡眠。

Some were given a caffeine pill equivalent to about four cups of coffee and others received a placebo instead.

其中有些人服下一顆相當於四杯咖啡的咖啡因藥片，其他人則拿到安慰劑。

Even when the volunteers swallowed the caffeine pills six hours before bedtime, they spent significantly less time in the light stages of sleep.

即便自願者是在睡前六小時吞下咖啡因藥片，他們的淺眠階段依舊大量減少。

And that can have detrimental effects on daytime function, the authors report.

而論文作者指出這點會對日間大腦運作產生負面後果。

- It"s sort of just stuck in this loop where you"re not sleeping because you drink too much coffee and then you wake up in the morning and you"re not well rested and you"re drinking more coffee just to stay awake in the day.

你會困在一種循環：喝太多咖啡因而睡不好。隔天早上起來休息不夠，所以喝更多咖啡來撐過這天。

- Sound familiar?

你也是這樣嗎？

Here"s the good news.

這邊有些好消息。

If you cut yourself off by 2:00 you typically won"t have trouble falling asleep.

只要在兩點以後不碰咖啡，你大概就不會有睡眠問題。

That"s because the half-life of caffeine is around five hours.

那是因為咖啡因的半衰期大概是五個小時。

And so most of its stimulating effects will wear off well before the lights go out.

這樣晚上關燈睡覺前，大部分的刺激效果就會消退。

And if you also limit your consumption, well then coffee can actually offer a number of health benefits.

並且如果你有在注意攝取量的話，事實上咖啡會帶來不少健康益處。

Research shows that it can help with everything from memory, to exercise, to your relationships with your colleagues.

研究結果顯示咖啡對你的記憶、運動效果、職場關係都有幫助。

And that"s great because for some of us, coffee is just something we"ll just never give up.

這真是太好了，因為對某些人來說，咖啡可是我們永遠不想放棄的東東啊！

校譯： 全民英語編輯部