Placeholder Image

字幕表 動画を再生する

審査済み この字幕は審査済みです
  • After I took the SAT, I was so exhausted I wanted to sleep for days, but really, I just sat there for a few hours.

    SAT を受けた後、疲れ果てて何日も寝ていたけど、実際には数時間座っていただけです。

  • How can sitting there and thinking wear you out?


  • Hey Brainiacs, Julia here for DNews.

    やあ、頭脳派諸君、 DNews のジュリアです。

  • Have you ever been really tired after spending all day sitting around at school?


  • How can you be so exhausted from literally just sitting all day?


  • Why is learning so tiring?


  • Well, let's start with the body's energy usage.


  • About 30% of the calories you eat go towards maintaining your current muscle mass.


  • While our brain only makes up 2% of your body weight, it gobbles up 20% of the energy you take in.


  • One study published in Proceedings of the National Academy of Sciences USA found that 2/3s of the energy the brain uses goes to the firing of cells.


  • But the other third, is basically just brain maintenance.


  • So where does that energy come from?


  • Most of the energy the brain eats up is in the form of glucose from the things we eat.


  • When neurons in the brain fire, they need extra oxygen and glucose from nearby capillaries.


  • So scientists think that when performing a difficult mental task, the neurons would eat up more glucose.


  • And so there'd be less glucose in the bloodstream if you'd measure it after something like a tiring test.


  • And that is what some studies show.


  • Another study published in the journal Physiology Behavior found that there was less blood glucose in the bloodstream, which the researchers thought was linked to neurons firing on all cylinders.

    また、『Physiology Behavior』誌に発表された別の研究では、血中のブドウ糖が少なくなっていることがわかりました。

  • Another more recent study published in Human Factors: The Journal of the Human Factors and Ergonomics Society found that people get more exhausted when exerting both physical and mental faculties than when just simply working out.

    『Human Factors』誌に掲載された、より最近の別の研究『The Journal of the Human Factors and Ergonomics Society(人間工学会誌)』に掲載された別の最新の研究によると、人は単に運動しているときよりも、肉体的・精神的な能力を発揮しているときの方が、より疲労が蓄積することがわかりました。

  • The researchers specifically noted that when performing both physical and mental tasks, there was strong activity in the prefrontal cortex and there was lower blood oxygen levels in the PFC after a combined physical and mental task than when just doing physical work.


  • So following that line of thought, eating foods high in glucose should improve mental performance.


  • One review published in the European Journal of Pharmacology found that glucose can improve memory, but it really depends on the dose and the person.

    『European Journal of Pharmacology』誌に掲載されたある総説によれば、ブドウ糖は記憶力を向上させますが、その効果は投与量と人によります。

  • So there is something about mental tasks that makes our brains work a little harder and take up a little more glucose.


  • But why does it actually make us tired?


  • Well, results are mixed.


  • One small study published in the journal Psychosomatic Medicine found that people who just completed memorization and attention tests ate 200 more calories than those who just relaxed.


  • But it might be more than just brain drain.


  • One scientist, Claude Messier of the University of Ottawas, thinks maybe it's just stress, that those students were just stress eating, which is a very real thing.


  • So while test taking might be zapping your energy, maybe it's the classroom you're in.


  • Matt Lieberman explains how carbon dioxide in the classroom might make for slower brains.


  • It turns out even levels as low as 1,000 parts per million can reduce the brain's ability to focus and function properly.

    二酸化炭素の濃度が 1,000 ppm程度でも、脳の集中力を低下させ、正常に機能しなくなることがわかりました。

  • And considering that we produce carbon dioxide every time we exhale, that's a big old problem.


  • So what was the last time you felt tired after a test?


  • Tell us about it down in the comments below.


  • Don't forget to hit those like and subscribe buttons to keep coming back to DNews. We have new episodes every day of the week.


After I took the SAT, I was so exhausted I wanted to sleep for days, but really, I just sat there for a few hours.

SAT を受けた後、疲れ果てて何日も寝ていたけど、実際には数時間座っていただけです。

審査済み この字幕は審査済みです

ワンタップで英和辞典検索 単語をクリックすると、意味が表示されます