- Triss, can you scratch my back? - Yeah, right there? - Yeah.

- Triss，你可以幫我抓抓背嗎？- 好喔，那裡嗎？- 對。

- Down a little bit. - OK. - Yeah. Oh, yeah, that's it. Don't stop.

- 下面一點。- 好。對了。喔對，就是這樣。不要停。

Hey, guys, Tara here with an answer to one of life's greatest mysteries: Why is scratching an itch always make it worse?

嗨各位，我是 Tara，今天將要為大家解答一件生活中的奧秘：為什麼我們抓癢時會越抓越癢呢？

Every one of us has been bitten by a mosquito at some point.

我們每個人都一定有被蚊子咬的經驗。

It actually happened to a friend of mine last week,

我的一個朋友就在上週被蚊子咬了，

and he ended up scratching it so hard he created an open wound, the size of a dime which is disgusting.

他抓得太用力，最後變成了一個破皮的大傷口，像一個硬幣一樣大，非常噁心。

We've all been there, trying to break the habit of procrastination but failed eventually.

我們都有過這樣的經驗，嘗試戒掉拖延的壞習慣，但最後卻還是失敗了。

I understand her feeling of losing the loved ones. We've all been there before.

我明白她失去親人的感受，我們都曾經歷過。

But we've all been there, well, some of us.

但我們都有過這樣的經驗，有些人啦。

Most of us get a bug bite, we scratch it for a while and then in a few days it goes way, and we never think about it again.

我們大部分的人被蟲咬後，抓一下，然後過幾天包就會消失，而我們再也不會想起它。

Some studies show that chronic loneliness increases the likelihood of early death.

一些研究顯示了長期的孤獨會提高早逝的可能性。

Many rural villages are still trying to solve the chronic shortage of health centers and clinics.

許多偏遠鄉村仍在努力解決保健中心和診所長期短缺的問題。

The old man has been hospitalized with an acute case of pneumonia for weeks, and doctors fear that he may not make it through the night.

這名老人已因為急性肺炎住院好幾週了，醫生擔心他可能撐不過今晚。

The acute economic crisis may have passed but the chronic challenges remain.

嚴重的經濟危機或許已經過去了，但長期的挑戰依然存在。

A blind person often has an acute hearing.

Sarah has been suffering from a chronic back pain for years.

Sarah 多年來飽受長期背痛所苦。

Since my grandma suffers from chronic arthritis, she has been walking with a cane for over ten years.

由於我的奶奶患有慢性關節炎，她仰賴手杖走路超過十年了。

But believe it or not, there are millions of people out there who suffer from chronic itching.

但不論你相不相信，世界上有幾百萬人深受慢性搔癢症所苦。

Conditions like eczema and even cancer or kidney failure can worsen it, and in many cases it can have a serious impact on someone's life.

症狀像是濕疹，癌症或腎衰竭甚至會讓你癢得更嚴重，在許多案例中，癢甚至會影響到一個人的生活。

Most of the crimes boil down to lack of money.

大部分犯罪行為的主要原因歸根究柢都是因為缺錢。

Ｗe didn't fight a lot, but when we did, it seemed to always boil down to the same issues.

我們不常吵架，但一旦吵架了，吵的都是同樣的事情。

Serotonin is a neurotransmitter that regulates tons of different functions in your body.

血清素是一種神經遞質，負責調節許多身體中不同的功能。

Your mood, your memory, your sleep, your appetite, even blood clotting.

你的情緒、記憶、睡眠、胃口，甚至是凝血功能。

In the 1970s, jogging became popular, and trainers were designed specifically for comfort while jogging came in.

慢跑在1970年代很受歡迎，於是專門為慢跑設計的舒適跑鞋開始流行。

Reports of a major accident on the motorway are just coming in.

剛剛收到高速公路上發生重大事故的報導。

The family doesn't have much money coming in at the moment because their business failed.

那個家庭因為經商失敗，所以目前沒有多少收入。

We need expert advice, and that's where you come in.

我們需要內行人的建議，這正是用得到你的地方。

I suggested (that) you keep these maps with you because they might come in handy some day.

我建議你把這些地圖帶在身上，因為它們有天可能會派上用場。

It produces feelings about happiness and well-being but it also controls pain, and that's where the itching part comes in.

血清素也會製造快樂和幸福的感覺，但它同時也控制了痛覺，這也是「癢」的來源。

Chu Fang Chen, as a researcher at Washington University, and he's been conducting studies over the years to see what produces the urge to itch.

華盛頓大學的學者 Chu Fang Chen，已經研究造成癢的原因許多年。

His most recent one involved mice who were genetically engineered to produce no serotonin.

他最新的實驗對象是基因改造的老鼠，牠們體內沒有血清素。

And he found that when those mice were injected with a chemical to induce itching, they had almost no urge to scratch.

他發現當這些老鼠被注射引發搔癢感的化學物時，他們幾乎不會有抓癢的動作。

Meaning that the urge to scratch an itch begins as soon as serotonin leaves your brain and reaches the irritated spot,

這代表一旦血清素離開大腦到達患部，你就會產生抓癢的欲望，

so whenever we scratch an itch we're actually doing so because the pain of scratching temporarily overrides the itchy feeling.

所以我們在抓癢時就是這麼回事因為抓癢造成的疼痛感會覆蓋過癢的感覺。

The problem is that that pain causes your brain to release more serotonin, which intensifies the itch even more.

問題是這種痛覺會讓你的腦釋放更多的血清素， 血清素會加劇你癢的感覺，所以這基本上是個循環。

The boy's father told him to get rid of his old sneakers.

那個男孩的爸爸叫他把那雙舊球鞋丟了。

YouTube is getting rid of its video editor and photo slideshows due to lack of use.

由於影片編輯器和照片幻燈片缺乏使用，所以 YouTube 要去除這兩項功能。

It took me over half an hour to get rid of that salesperson.

我花了半個多小時才擺脫那位銷售人員。

So it's essentially a feedback loop where you're constantly scratching harder and harder to get rid of the itchy feeling, but all you're doing is really making it even more itchy.

當你一直抓癢，越抓越用力，想要擺脫癢的感覺時，你在做的只是讓它越來越癢。

It make sense but it does bring up another interesting question: Why does serotonin cause an itchy sensation to begin with?

這也引發另一個有趣的問題：為甚麼血清素帶來的感覺會被稱為「癢」呢？

Well, according to Chen, it has to do with GRPR neurons, which are a group of brain cells known to increase itchy sensations.

根據 Chen 的說法，這跟一組腦細胞 GRPR 神經元有關，GRPR 神經元會造成癢的感覺。

A serotonin starts rushing to the part of your body that's irritated,

its wires basically get crossed, and it activates those GRPR neurons which intensifies the itch even more.

線路被連接起來，刺激 GRPR 神經元，加劇癢的感覺。

Chen believes that people who suffer from chronic itching could find relief once a therapy is developed to block the receptor that cause the serotonin to activate those neurons.

Chen 相信只要能夠發展出攔阻神經元傳遞血清素到感覺器官的治療方法，長期受癢所苦的人就可以得到解脫。

Until then, the best solution seems to be lots of anti-itching cream and other mittens, the softer the better.

在此之前，最好的治療方法似乎只有抗癢霜、防抓手套，軟一點的更好。

這是我的建議啦，不是 Chen 的。

What do you guys think? Have you ever scratch the itch so hard that made you bleed?

你們覺得呢？你有沒有因為抓癢抓到流血的經驗？

Feel free to share your experiences with us in the comments down below.

請在下方留言，跟我們分享你的經驗吧。

And as always, thank you guys for watching.

炎炎夏日是蚊子愛出沒的季節，想想小時候總會被叮得滿腳都是包，抓到流血還是很癢，但其實許多慢性疾病更會使我們癢到無法入睡，只能邊睡邊抓，那才叫做痛苦難耐啊！到底為什麼會感覺癢呢？而且為什麼會越抓越癢呢？就由影片來為你解答吧！！！ 1We've all been there.    0:31  這句話從字面上是指「我們都去過那裡」，因此延伸為「我們都曾有過這樣的經歷」的意思，就等同於...