六分钟｜为什么你需要睡个好觉？

Hello, this is 6 Minute English from BBC Learning English. I'm Georgie, and we're ready to start, Phil… Phil?! --Oh, sorry, Georgie, I was er, just, catching forty winks… you know, getting some shut-eye, dozing, taking a nap... I was sleeping! --Sleeping at work! Phil, how could you? I know, I know. --Sorry, I… I didn't sleep well last night.

I'll forgive you this time, but make sure you go to bed early tonight because getting a good night's sleep is incredibly important. For example, did you know that people who get enough sleep live about five years longer than people who don't? --Wow, so a good night's sleep can lengthen your life. In this programme, we'll be finding out more about the benefits of sleep, and, as usual, learning some useful new vocabulary as well.

But first, now that you've woken up, I have a question for you. Do you know how much of the average person's life is spent asleep? Is it: a) a half? b) a quarter? or, c) a third? --Hmm, I think we spend about a third of our lives sleeping. --OK, well I'll reveal the correct answer at the end of the programme.

The question of why humans sleep is not easy to answer. In terms of evolution, why would it make sense to go unconscious every night, leaving yourself vulnerable to danger? It can only mean that the benefits gained from sleep are huge. Here, science journalist, Ginny Smith, explains some of these benefits to BBC Radio 4 programme, Inside Science:

So we've probably all experienced this, that if you've had a bad night sleep and then you try and do some work you just can't concentrate - your brain isn't in the right state to take in new information. But we also need to sleep after we've learnt new things because that's when our brain consolidates the information - takes it from short-term storage to long-term storage, fits it in with other things we already know, that old adage of if you've got a problem sleep on it, your brain does actually work on things during the night, and you can often wake up and have solved the problem in your sleep.

When we sleep, our brains refresh, leaving us feeling rested in the morning. But after a bad night's sleep it's more difficult to concentrate. We can't take in, or understand, new information. We also have the saying, if you've got a problem, sleep on it. To sleep on it means to delay making a decision until you've had time to think about it. But that also turns out to be true scientifically speaking - during sleep, your brain really can work out problems and find solutions.


But what about the other side of the story? What happens when you get too little sleep, or none at all? Here's Ginny Smith again, talking to BBC Radio 4 programme, Inside Science:

Sleep deprivation is a form of stress, and we know that when you are stressed your sort of fight-or-flight response is activated and that causes all these changes in your body that focus on immediate survival over long-term health. But if we are chronically stressed - money worries, or a stressful job, or something that's going on forever, or life, or chronic sleep deprivation that's causing that level of stress, then you might constantly have a damped down immune system which can then lead to all these knock-on problems.

Having none or too little of something important is known as deprivation. Sleep deprivation is stressful for the body – so stressful that it activates a fight-or-flight response, changes in the human body in response to a life-threatening situation which make us either stay and fight the threat or run away from it. As well as a fight-or-flight response, the stress of not getting enough sleep over a longer period also creates problems including heart disease and a weakened immune system. Lack of sleep has these knock-on effects, it causes other things to happen, but not directly.

Now do you see why it's so important to get a good night's sleep, Phil? Plus, it will stop you sleeping at work again! Right, I think it's time to reveal the answer to my question. --Yes, you asked me how much of the average person's life is spent asleep, and I said it was about a third. --Which was… the correct answer! Assuming you sleep eight hours a day, the average person will sleep for 229,961 hours in their lifetime or around one third of their life.

OK, let's recap the vocabulary we've learned starting with the phrases catch forty winks, get some shut-eye, doze and take a nap, all of which mean to sleep. When someone takes in information, they understand it. If you have a problem and you sleep on it, you delay making a decision until you've had time to think about it. Deprivation is an absence or too little of something important such as food or sleep. The fight-or-flight response describes changes in the human body in response to a dangerous situation which make us either stay and fight the threat or run away from it. And finally, if something has a knock-on effect,itcauses other results indirectly.

Once again our six minutes are up, but remember to join us again next time for more trending topics and useful vocabulary, here at 6 Minute English. Goodbye for now! Bye!

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