You should be asleep, but you're watching

你早該睡了，但你仍在看著手機上的影片，

a video on your phone and tomorrow you'll wake up,

而你明天早上會起床，

and go to work, where you'll stare

然後去工作，並且盯著電腦，

at a computer for eight hours.

長達八小時。

When you get home, you might even watch a movie on TV.

當你回到家，你可能甚至會看個電視上的電影。

So if you're anything like the average American adult,

所以如果你是一個普通的美國成年人，

you spend more than seven hours a day

你一天會花上超過七個小時，

staring at digital screens.

用來盯著電子螢幕。

So what's all this screen time actually doing

那麼這些花在電子螢幕上的時間，

to your body and brain?

究竟對你的身體和大腦有甚麼影響 ?

Surprise, surprise, humans did not evolve to stare

號外，號外，

at bright electronic screens all day

人類演化並非是為了成天盯著電子螢幕看。

so our eyes are suffering the consequences.

因此我們的眼睛正在承受著這樣做的後果。

An estimated 58% of people who work on computers

使用電腦工作的人中，

experience what's called computer vision syndrome.

大約有 58% 得到了所謂的電腦視覺症候群。

It's a series of symptoms that include eye strain,

它包含了一系列的症狀，包含眼睛疲勞、

blurred vision, headaches, and neck and back pain.

視野模糊、頭痛、頸部與背部疼痛。

And in the longterm this amount of screen time

而長期下來，這樣的電子螢幕使用量，

could be damaging our vision permanently.

可以永久的傷害到我們的視覺。

Since 1971, cases of nearsightedness in the US

從 1971 年開始，美國近視的病例

have nearly doubled, which some scientists

幾乎成長了一倍，

partly link to increased screen time.

有一些科學家將部份原因歸咎於電子螢幕使用時間。

And in Asia today, nearly 90%

而在現在的亞洲，則有將近 90% 的

of teens and adults are nearsighted.

青少年與成年人近視。

But it's not just the brightness of our screens

但不只是螢幕的亮度會對我們造成影響，

that affect us, it's also the color.

它的色彩也扮演了很大的角色。

Screens emit a mix of red, green, and blue light.

螢幕射出混合了紅、綠、藍光的光束。

Similar colors to sunlight.

接近陽光的色彩。

And over a millennia it was blue wavelengths in sunlight

而千年以來，就是陽光中的藍光，

that helped us keep our circadian rhythms

幫助我們身體的生理時鐘，

in sync with our environment.

與我們的環境維持同步。

But since our circadian rhythms are more sensitive

但正由於我們的生理時鐘對藍光更為敏感，

to blue light than any others, a problem occurs

當我們在晚上使用螢幕時，

when we use our screens at night.

問題就產生了。

Typically when the sun sets

一般來說，當太陽下山，

we produce the hormone melatonin.

我們會產生一種叫褪黑激素的賀爾蒙。

This hormone regulates our circadian rhythms,

這種賀爾蒙維持我們生理時鐘的規律，

helping us feel tired and fall asleep.

幫助我們感到疲憊與入睡。

But many studies have found that blue light

但有許多研究發現，

from screens can disrupt this process.

螢幕的藍光可以干擾這個過程。

For example, in one small study,

例如，在一個小型實驗中，

participants who spent four hours reading e-books

連續五個晚上睡前先花四個小時閱讀電子書的受試者，

before bed for five nights, produced 55% less melatonin

比起閱讀紙本書的受試者，

than participants that read print books.

少產生了 55% 的褪黑激素。

What's more, the e-book readers reported

更甚者，電子書的閱讀者表示，

that they were more alert before bed,

他們在睡前變得更警覺、需要花更多時間入睡，

took longer to fall asleep and reach restorative REM state,

與進入到放鬆的快速動眼期，

and were more tired the next morning.

隔天早上也更加疲憊。

But perhaps the most concerning changes

但恐怕在所有使用螢幕造成的影響中，

we're starting to see from all this screen time

最令人擔憂的改變，

is in kid's brains.

發生在兒童的腦袋。

An ongoing study, supported by the NIH

一個由美國衛生研究院贊助的計畫，

has found that some preteens who clocked

發現每日使用 7 小時螢幕的兒童中，

over seven hours a day on screens

有一些人，

had differences in a part of their brain called the cortex.

在大腦一個稱作「皮質」的區塊出現異狀。

That is the region responsible

皮質是一個，

for processing information from our five senses.

負責處理我們五感的區域。

Usually the cortex gets thinner as we mature,

一般來說，隨著年紀增長皮質會變得越變越薄，

but these kids had thinner cortexes earlier than other kids

但這些兒童皮質的薄化，相較於其他螢幕使用時間較少的兒童，

who spent less time on screens.

卻早了許多。

Scientists aren't sure what this could mean

科學家並不確定這樣的狀況會對這些兒童，

for how the kids learn and behave later in life,

往後的學習與行為造成甚麼影響，

but the same data also showed that kids who spent

但同一份研究也顯示，

more than two hours a day on screens

每日使用超過兩小時螢幕的兒童，

scored lower in thinking and in language skill tests.

在思考與語言考試上獲得較低的分數。

To be clear, the NIH data can't confirm

簡單來說，美國衛生研究院的資料無法證實，

if more time spent staring at screens causes these effects,

這些效果是否真的是由更多的螢幕使用時間造成，

but they'll have a better idea of any links

但隨著在接下來的十年，

as they continue to follow and study

對這些兒童繼續追蹤與研究，

these kids over the next decade.

他們會對兩者的關聯有更深入的了解。

It's no doubt that screens have changed

毫無疑問的，

the way we communicate, but only time will tell

電子螢幕為我們的溝通方式帶來了改變，但只有時間才能告訴我們，

what other changes are on the horizon for human kind.

還有什麼其他的改變正在等待著人類。