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  • It's 11 PM.

  • You should be asleep, but you're watching

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

  • and go to work, where you'll stare

  • at a computer for eight hours.

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

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

  • you spend more than seven hours a day

  • staring at digital screens.

  • So what's all this screen time actually doing

  • to your body and brain?

  • Surprise, surprise, humans did not evolve to stare

  • at bright electronic screens all day

  • so our eyes are suffering the consequences.

  • An estimated 58% of people who work on computers

  • experience what's called computer vision syndrome.

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

  • blurred vision, headaches, and neck and back pain.

  • And in the longterm this amount of screen time

  • could be damaging our vision permanently.

  • Since 1971, cases of nearsightedness in the US

  • have nearly doubled, which some scientists

  • partly link to increased screen time.

  • And in Asia today, nearly 90%

  • of teens and adults are nearsighted.

  • But it's not just the brightness of our screens

  • that affect us, it's also the color.

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

  • Similar colors to sunlight.

  • And over a millennia it was blue wavelengths in sunlight

  • that helped us keep our circadian rhythms

  • in sync with our environment.

  • But since our circadian rhythms are more sensitive

  • to blue light than any others, a problem occurs

  • when we use our screens at night.

  • Typically when the sun sets

  • we produce the hormone melatonin.

  • This hormone regulates our circadian rhythms,

  • helping us feel tired and fall asleep.

  • But many studies have found that blue light

  • from screens can disrupt this process.

  • For example, in one small study,

  • participants who spent four hours reading e-books

  • before bed for five nights, produced 55% less melatonin

  • than participants that read print books.

  • What's more, the e-book readers reported

  • that they were more alert before bed,

  • took longer to fall asleep and reach restorative REM state,

  • and were more tired the next morning.

  • But perhaps the most concerning changes

  • we're starting to see from all this screen time

  • is in kid's brains.

  • An ongoing study, supported by the NIH

  • has found that some preteens who clocked

  • over seven hours a day on screens

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

  • That is the region responsible

  • for processing information from our five senses.

  • Usually the cortex gets thinner as we mature,

  • but these kids had thinner cortexes earlier than other kids

  • who spent less time on screens.

  • Scientists aren't sure what this could mean

  • for how the kids learn and behave later in life,

  • but the same data also showed that kids who spent

  • more than two hours a day on screens

  • scored lower in thinking and in language skill tests.

  • To be clear, the NIH data can't confirm

  • if more time spent staring at screens causes these effects,

  • but they'll have a better idea of any links

  • as they continue to follow and study

  • these kids over the next decade.

  • It's no doubt that screens have changed

  • the way we communicate, but only time will tell

  • what other changes are on the horizon for human kind.

It's 11 PM.


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B1 中級

何を見つめて一日中画面であなたの脳と体に何をしています。 (What Staring At A Screen All Day Is Doing To Your Brain And Body)

  • 104 9
    Liang Chen に公開 2021 年 01 月 14 日