Episode 6 Bang Goes the Theory


Episode 6

Science series. Dallas Campbell downs his toothbrush to discover what causes tooth decay and gum disease, and Dr Yan Wong explains why refreezing food is not a great idea.


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Transcript


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Tonight, Jem takes part in an experiment

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to discover how electric light

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may be playing havoc with our sleeping patterns.

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It's morning light that is so important

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for setting the body clock.

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OK, this is it. This is truly grim.

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And Dallas downs his toothbrush

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to find out exactly what causes tooth decay and gum disease.

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-Have a smell.

-Eurgh! It's stinky!

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That's Bang Goes The Theory, revealing your world with a bang.

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Electric light, something we take totally for granted.

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The flick of a switch, we get ourselves some indoor sunshine.

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But worryingly, scientists are beginning to understand

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that living under artificial light may have an unexpected effect on our bodies.

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No one really knew why until a recent discovery

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revealed a whole new way in which our eyes work.

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Our eyes are one of the best-studied organs in medical science

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yet only recently did we discover they do far more than simply see.

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Just a few years ago, researchers at Oxford University

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found that our eyes have another, subconscious response to light,

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one that deeply affects our daily lives.

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If only I could get through this impossible dark room door.

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I'm going to find out how it works from the man who discovered it,

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Professor Russell Foster.

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OK, I'm going to plunge you into darkness now.

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OK, that's pretty dark now.

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Professor Foster starts by demonstrating

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the two ways our eyes consciously see.

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These are the classic tests to find out if you're colour-blind.

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Exactly. Can you recognise any numbers in there?

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I could tell you it's black on the outside, then sort of white there,

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and this is neither black nor white, but actual colours, there's none.

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It's just shades.

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So I'm now going to increase the light a little bit.

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Now you can tell that there's like reds and browns appearing

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and then there's sort of greens and blues.

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-I'm going to go for that as a six.

-The most important part of the eye

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are the light sensors or the photoreceptors.

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There's the rods, which are used for dim light vision.

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They're essentially brightness detectors.

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And then the cones, which allow us to see colour.

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In fact, there are three different types of cone in our eye.

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Each of those cones is peaking broadly in the blue part

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of the spectrum, the green part of the spectrum

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and one in the orangey red part of the spectrum.

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When you stimulate all those three receptors maximally,

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as you would with sunlight, it appears white.

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So to make artificial sunlight, surely all you need is to fool

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the eye with the right mix of red, green and blue, isn't it?

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Well, that's what we'd assumed.

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Until Professor Foster made his stunning discovery.

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A third type of light sensor in our eye.

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A colleague came across a lady who had a very strange visual defect

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whereby she'd lost all of her rod and cone cells.

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She said she had no conscious light detection but we said,

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"OK, just tell us when the lights were on and off." And quite remarkably, she could always do it.

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-Wow.

-And so there's another, yet another light sensor in the eye.

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Not the rods and not the cones, but it's a group of ganglion cells.

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They have a peak in sensitivity in the blue part of the spectrum

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and it's at a colour or a wavelength which basically matches

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the blueness of a blue sky.

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These special blue sensors are nothing to do with actually seeing.

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We thought of these new receptors in the eye as body clock light sensors.

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We have an internal body clock which is constantly adjusting

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and fine-tuning every aspect of our physiology.

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So it contributes to your overall alertness, your ability to constrict your pupil,

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adjust your body clock, and probably a whole raft

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of other things we're just discovering.

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The Professor thinks these sensors evolved in our early ancestors,

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allowing them to take subconscious time cues from sunlight.

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And they worked perfectly, until engineers like me got involved.

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For millions of years, the only lights we had, really,

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were sunlight and firelight.

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But with the advent of electricity, things changed fairly dramatically.

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This electric arc actually gives off pretty good fake sunlight.

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Look, if I split up its colours. It's a very even spread on the spectrum.

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We've got red, yellow, green, blue, right the way up here.

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It's almost identical to the range of colour in natural sunlight

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with plenty of that blue that your body clock needs.

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Trouble is, it's far too bright to use at home.

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Plus, it's full of dangerous ultraviolet. Protective masks indoors? Just not a good look.

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So I'll move on swiftly, just like mankind did,

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to this, the incandescent bulb, the kind of standard lightbulb.

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Electricity can make a thin wire very hot

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and at a few thousand degrees, it'll start to glow white hot.

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But this is no ordinary wire, this is tungsten wire,

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which melts at well over 3,000 degrees Celsius.

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I have to put a glass over the top of it,

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and suck the air out of it, so that wire doesn't burn when it gets hot.

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There you go. It's now sat in a vacuum.

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There we go. That is a lightbulb. It's like a miniature star in a jar.

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Although this looks like sunlight, the mix of colours is not the same.

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It has less in the way of blue and violet in it

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than maybe bright daylight would have, so in light like this,

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there's less of the colour those sky blue sensors respond to.

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But traditional bulbs like this are too inefficient for moderate use.

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Making artificial light through extreme temperatures,

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it requires a relatively large amount of power for not that much light.

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So in our energy efficient modern age,

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we've moved towards lamps that operate

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from an entirely different phenomenon.

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Fluorescent lights work a bit like the Northern Lights,

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where electrical energy gives the sky an eerie glow.

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I'm pumping the air out of this tube to recreate the upper atmosphere.

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A blast of a few thousand volts should make that low pressure air

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produce an almost magical effect.

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Look at that. I mean, it's a weird, pink light,

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as you may expect from a kind of home-made aurora.

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Of course, it's not magic. It's atomic emission of pure cold light.

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I'm pretty chuffed with it. Though it's not much like sunlight yet,

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but I can fix that. How do you go from that beautiful pink

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to the classic white fluorescent we're used to?

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Well, what you have to do is coat the inside of the tube with a powder,

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a mix of chemicals called phosphors

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that gives off a whole range of colours

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when stimulated by the UV light that's also given off by those atoms.

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Let's see how this goes.

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Oh!

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It's a pretty white light.

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All strip lights work like this,

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and it's what's coiled up inside low-energy bulbs.

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It's still made up of different colours, but this time,

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instead of it being a smooth spectrum from red to violet,

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instead it's distinct bands of colour.

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The different bands are produced by different glowing powders.

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Now, you only need a few bands to trick the eye into seeing white,

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but unless the right sky blue is there,

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there's nothing for those newly discovered receptors.

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Our modern lives are a jumble of different artificial lights

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and it could be playing havoc with our body clock.

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I'm going to do a little experiment and I think it's a world first.

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I'm going to see how much of that blue light

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I'm exposed to over a typical 24 hours and when.

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Which means carrying this kit around with me

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to analyse the spectrum wherever I go.

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I'm hoping Professor Foster can tell me what all this

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might mean for my body.

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OK, Jem, so what we've looked at here is the amount of light

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in the blue, the blue skylight at 480 nanometres.

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-OK.

-It's very clear that you went outside just after nine o'clock

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and the light levels have just rocketed.

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-They've gone absolutely huge.

-I cycle to work.

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It takes about half an hour. This day, I had to pop out and do a bunch of other stuff as well.

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And that's really important, because it's morning light

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that's so important for setting the body clock. So, wittingly or not,

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you've seen light during the most important part of the day.

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So in the winter, when you're kind of going to work and it's dark

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and it's just getting light as you go into work quite often,

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are you effectively giving yourself jetlag?

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Your body's not sure what time of day it is.

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There's increasing evidence that's exactly what we're doing.

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I think there's an opportunity here. In the underground,

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in the tubes, we could have augmented lighting,

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we could actually try and provide a brighter morning light environment,

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-which would help stabilise internal time.

-Anything that makes travelling

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on the tube slightly better for you is a good thing.

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During the day, I'm only getting bursts

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of that all-important blue light when I go outdoors.

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So what's the deal with the artificial lights I'm using?

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-Here I am in the workshop.

-Oh, my goodness.

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This has got to be fluorescent light. You can tell that

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because of these sharp emission spectra in the blue,

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the green and the red, but you've got very little blue.

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So not only is it low, but it's actually lacking in blue light, which is what you want.

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Is there an effect on me of having such low light levels at work?

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The loss of blue light would have a distinct effect

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on your levels of alertness.

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Fluorescent lights give off very distinctive colours.

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-But they're not the only lights in my life.

-So what time of day?

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-This is midday.

-It's strange, because it's not fluorescent light,

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cos there's no great big peaks. Is this a computer screen perhaps?

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It's like talking to Derren Brown.

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Yes, that probably is a computer screen.

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You've got a nice blue enrichment there,

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which means that if you were looking at a computer screen like this

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at night, before you're going to bed, that blue enrichment

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could actually increase alertness and so significantly delay

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your tendency to fall asleep and go to bed.

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My lights at home are different again. Can he identify those?

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You don't have any big peaks in it, so it's not fluorescent light.

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But it could be something like a halogen light,

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and so you see the broad tungsten light,

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relatively enriched in the red compared to the blue.

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-You've got those little halogen lights?

-Yes, I have.

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So if I wanted lighting in my home to make me feel alert,

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or at work, to make me feel alert, I'd be looking to have

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lighting that had a high enough proportion, and a high enough

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intensity of this blue, but then I wouldn't want too much of that

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in the evening, otherwise I'd stay alert when I wanted to go to sleep.

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Exactly. And this represents a huge problem

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for people who don't get out very much.

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If you're in a nursing home, with relatively dim light,

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you'll never get that bright exposure and the body clock

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will tend to drift through time. And also the various rhythms,

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so the rhythms that regulate your gut function or your brain function

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or your liver function will then start to drift apart slowly,

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and so you won't have very fine-tuned

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and well ordered physiology under those circumstances.

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I think that is a really, really interesting film.

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Off the back of that, there's obvious things you can do to help.

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Don't be looking at your computer before you go to sleep,

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and if you can, in the morning, go out and get a bit of sunshine.

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It makes sense. But armed with that knowledge, presumably we can start to develop

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technologies that are geared to how we've actually evolved,

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because clearly, as a species, we're not evolved to live

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-in the world we've created for ourselves.

-You're bang on the money.

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There are companies out there at the moment that are actually

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developing artificial lights that change their spectra during the day

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to sort of match what daylight does.

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My view, though, no substitute for daylight.

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Although our eyes adjust brilliantly to different light levels,

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it can actually be thousands of times brighter outside

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-than under domestic lights.

-You can't beat the sun.

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But in a country like this with pretty grim winters,

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anything you could do to help you feel better is a good thing.

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For example, I do feel really rubbish in the winter,

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so I bought a seasonal affective disorder lamps, you know those?

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But after watching your film, I've realised why I was disappointed.

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I was using them in the evening after college,

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from seven to 11 o'clock or something,

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and now I know to have used them in the morning

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to actually kick off my body clock, yeah?

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Exactly. The strong morning light makes the biggest difference.

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-And coffee.

-And coffee.

-Very important.

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Interesting stuff there. Next up, it's Dr Yan.

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He's in the kitchen this week talking about refreezing.

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We've all been there. You take out a frozen chicken dinner

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and you don't eat all of it but you know not to refreeze it.

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But do you know exactly why that is? Dr Yan is about to explain all.

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Using six chicken breasts, a punnet of strawberries and some fresh carrots,

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I'm going to get to the bottom of this domestic dilemma.

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These two, I'm going to put straight back in the fridge.

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These two I'm going to leave on the side. But these, well,

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I'm going to put them in the freezer now but I'm going to defrost them

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and refreeze them every day for the next five days.

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The carrots and strawberries I'm going to put in the freezer, too.

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That's not the normal place for this stuff but it'll all become clear.

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Now all I need to do is wait.

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Right, this should be done now.

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We all know that water turns solid when it freezes.

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It forms rigid crystals of ice.

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Well, 75% of this chicken breast and in fact, 90% of these,

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actually is water, so these are basically just solid blocks of ice,

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and ice crystals can be nasty things if you're a carrot.

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Food like this is made up of individual cells.

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Imagine them as tiny balloons filled with water.

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When they're not frozen, they keep the carrot nice and crunchy,

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but that all changes when the cells begin to freeze.

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Now, ice crystals inside the carrot act like microscopic needles,

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puncturing the cells.

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While it's frozen, you don't notice any difference,

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but as it defrosts, the water all oozes out.

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Which leaves the cells saggy and empty

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and us with a floppy, leaky carrot. Eurgh.

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And the strawberries, well, they're even worse. Look.

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The effect on meat is not nearly so severe

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but the same principle applies. But that's just it.

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It's only physical damage. Not very nice to eat, maybe,

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but totally harmless. There is something else

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we need to worry about, though. Bacteria.

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We all know that harmful bacteria on food can give you a dodgy tummy.

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On something like this, you could easily expect there to be

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10,000 bacteria per square centimetre.

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But under the right conditions, bacteria can quickly multiply

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to 10 or even 100 million per square centimetre,

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and that's when they're likely to make you ill. So does freezing,

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thawing and refreezing chicken make the bacteria any more harmful

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than just leaving them in the fridge or out on the side?

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Here we go. Every morning for five days, I'm going to take the chicken

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out of the freezer to defrost and every night put it back in again

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to refreeze. Then, I'm sending my refrozen chicken breast,

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along with the one I left in the fridge

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and the one that's been at room temperature the whole time, to be tested at a lab.

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Fantastic.

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Now, here are the results.

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The lab wouldn't actually send me back the samples

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because they were so contaminated, but this is what they found.

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Any coloured spots you see are harmful coliform bacteria.

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These are the results from the fridge chicken. There's not that many spots.

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There's a pair there and another two spots there

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but, you know, that's not that many. I'd probably eat that one.

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Here are the results from the chicken left out on the side.

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Loads of bacteria. The blue one is E.Coli. You've probably heard of it.

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You don't want to be eating lots of those. They thrive in a danger zone

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between five and 55 degrees Celsius.

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Now for the moment of truth. My refrozen chicken.

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Whoa, look at that, there's loads of coloured dots.

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There's fewer red ones than in the chicken left out on the side

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but there are three E.Coli there and, together with the others,

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enough to make you ill. The temperature's made the difference.

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Every time this chicken was defrosted, parts of it

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entered that temperature danger zone, from the first few minutes.

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And they stayed there until the chicken was put back in the freezer

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many hours later, allowing the bacteria to multiply the whole time.

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So it's not the freezing or refreezing that's the problem,

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it's the time the bacteria spend in the danger zone

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while the food defrosts. And it's not just raw meat, either.

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The same applies to re-freezing old cooked food.

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The bacteria will still be there lying in wait.

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I've just noticed a really interesting phenomenon.

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Dr Yan, he's done a few experiments in kitchens

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over the last few years, and every time, he's in a different kitchen.

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-Not only is he a brilliant scientist, he's also a property magnate.

-Nothing would surprise me about Dr Yan.

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What I didn't quite get, surely with all those bacteria,

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once you cook it, get it to a couple of hundred degrees,

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-it kills the bacteria anyway?

-The heat does kill them

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but it's not the bacteria themselves that cause illness,

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it's the toxins they release as they're metabolising in your body.

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So, for example, nasty E.Coli. You can kill the actual bacteria

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in the heat of the food, and you can break down some of the toxins that it produces, but not all of them,

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-and it's the remaining toxins that make you ill.

-Interesting.

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We're going to stay on the Dr Yan lovefest theme.

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Here is his weekly brainteaser. What is this?

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-The moon on a piece of paper.

-Not the actual moon, a picture of it.

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Very bright. That's not actually the conundrum.

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How many times would I have to fold this piece of paper in equal parts

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in order for it to be able to reach that moon 250,000 miles above me?

0:19:180:19:21

That's maybe 0.1mm thick. You are looking at thousands

0:19:210:19:24

of trillions of times thicker. I don't even think you could do it.

0:19:240:19:28

It's fewer than you think because actually, it's an exponential.

0:19:280:19:33

Cryptic clue. The answer's actually the answer to the ultimate question.

0:19:330:19:38

If that's confused your brain like it has mine, don't worry,

0:19:380:19:42

Dr Yan explains it perfectly well on our website, as always, /bang.

0:19:420:19:46

OK, coming up next, it's oral hygiene.

0:19:460:19:49

Now, like most people, I brush my teeth twice a day

0:19:490:19:51

to avoid getting fillings, but it turns out

0:19:510:19:54

that the main cause of tooth decay isn't due to lack of brushing.

0:19:540:19:58

And if you don't believe me, I've got 2,000 years of evidence to prove it.

0:19:580:20:01

Meet my three new friends, all former London residents.

0:20:010:20:07

This is a female Roman skull and if you look at the teeth,

0:20:070:20:10

there's a bit of wear and tear, but no tooth decay at all.

0:20:100:20:13

Surprisingly, very good condition. Fast forward to a mediaeval skull

0:20:130:20:17

and despite the lack of electric toothbrushes at the time,

0:20:170:20:21

again, very good teeth, no sign of any decay.

0:20:210:20:23

Cut to a post-mediaeval skull, and it's not pretty.

0:20:230:20:27

You can see here, very bad tooth decay. An abscess here.

0:20:270:20:32

It's not looking good. But why is that? One word, sugar.

0:20:320:20:36

This person's generation was the first in history

0:20:360:20:39

that could easily get hold of it, and they loved it.

0:20:390:20:43

And although they were probably no worse at brushing,

0:20:430:20:46

the sweet tooth alone was enough to set in the rot.

0:20:460:20:50

Allow me to demonstrate with this tooth-shaped cake.

0:20:500:20:53

When you eat something delicious and sugary like this,

0:20:530:20:56

it's not just you that gets a treat,

0:20:560:20:58

because inside our mouth, it's full of bacteria.

0:20:580:21:01

Most of the time, it's harmless and causes us no trouble.

0:21:010:21:04

Until, that is, you decide to eat or drink something sugary.

0:21:040:21:08

The bacteria thrive on sugar and as they digest it,

0:21:080:21:12

they create acid as a by-product.

0:21:120:21:14

It's this acid that is the problem because as it bathes the teeth,

0:21:140:21:18

it starts to dissolve the enamel.

0:21:180:21:20

This process is called demineralisation

0:21:200:21:23

and it happens every time you eat or drink something sugary.

0:21:230:21:26

Enamel is actually one of the strongest parts of the body,

0:21:280:21:31

but under attack from acid, mineral ions are removed

0:21:310:21:36

and that lattice structure is weakened.

0:21:360:21:39

If it continues to come into contact with acid,

0:21:390:21:42

eventually it'll collapse and that's when you get a cavity.

0:21:420:21:46

The acid gets to work in minutes.

0:21:470:21:49

Brushing at night can't undo the damage,

0:21:490:21:52

while brushing straightaway can even make it worse.

0:21:520:21:56

Thankfully for us, we have a natural weapon against tooth decay.

0:21:560:21:59

It's called saliva and it helps to neutralise

0:21:590:22:02

and wash away that acid, but it also contains mineral ions,

0:22:020:22:06

replacing the ones that are lost through acid erosion,

0:22:060:22:10

remineralising and helping strengthen

0:22:100:22:12

that latticework structure of the teeth.

0:22:120:22:16

But if you keep on eating sugary snacks,

0:22:160:22:18

your saliva can't keep up with the repair work.

0:22:180:22:21

What starts as a small cavity gets deeper and deeper.

0:22:210:22:24

And if the cavity expands and reaches the inner,

0:22:240:22:28

living part of the tooth, the dentine,

0:22:280:22:30

it's going to get painful because that's where your nerves are.

0:22:300:22:34

Most of us at this point are going to consider a trip

0:22:340:22:37

to the dentist, but if left unchecked, you're going to get

0:22:370:22:40

full-blown tooth decay and, eventually, your tooth will fall out.

0:22:400:22:45

The best way to avoid decay, then, is to avoid sugar.

0:22:450:22:49

So what's with all the brushing?

0:22:490:22:52

I'm going to find out by hanging up my toothbrush for five days.

0:22:520:22:56

OK, this is it. This is truly grim.

0:22:560:22:59

This is the last time I'm going to brush my teeth

0:22:590:23:02

for the next five days, so don't come anywhere near me.

0:23:020:23:06

It's day three. This is the third day I haven't brushed my teeth

0:23:060:23:10

and people are avoiding me, crossing the street as I walk past.

0:23:100:23:14

The smell is becoming unbearable almost.

0:23:140:23:18

-Are your teeth clean?

-Yeah.

-Let's see.

0:23:180:23:20

What do you think about Daddy's teeth?

0:23:200:23:23

Yucky.

0:23:250:23:27

Oh, dear, it's now day four of not being able to brush my teeth,

0:23:270:23:32

and I think they're looking pretty horrible.

0:23:320:23:35

They certainly feel fuzzy and grim.

0:23:350:23:38

-Have a smell.

-Eurgh, it's stinky.

0:23:380:23:41

This is horrible.

0:23:410:23:44

Everywhere I go, I kind of feel people are looking at me funny.

0:23:440:23:49

More funny than normal.

0:23:490:23:51

OK, no sugary snacks and my teeth haven't turned black,

0:23:540:23:58

but they are a bit furry. To find out what's going on,

0:23:580:24:02

I've come to Liverpool University's dental school.

0:24:020:24:06

They're pioneering a new camera that reveals the damage done

0:24:060:24:11

by five days of neglect. Not rot, but plaque.

0:24:110:24:14

It's difficult to see the plaque,

0:24:140:24:18

because it's white on white teeth.

0:24:180:24:20

If you look very closely, you can see some.

0:24:200:24:22

I'm a bit worried about that bit. That's a bit of last night's curry.

0:24:220:24:26

I think that's a bit of food debris.

0:24:260:24:29

But if we have a look at a different image we've taken

0:24:290:24:32

with our special camera, which is using fluorescence now,

0:24:320:24:37

then we can see some really quite heavy areas of plaque.

0:24:370:24:42

-So this orange stuff, that's plaque?

-That's plaque.

0:24:420:24:45

-That's quite a lot, isn't it?

-There is really quite a lot there.

0:24:450:24:48

Plaque is down to those same bacteria that produce acid.

0:24:480:24:52

Faced with a filthy mouth, they go wild,

0:24:520:24:55

billions of them forming a sticky, gooey mess all over your teeth.

0:24:550:24:59

It won't harm your teeth like acid does,

0:24:590:25:02

but if you don't brush away the plaque, it eventually hardens

0:25:020:25:05

and this time, it's your gums that pay the price.

0:25:050:25:08

So this is all stuff that's taken up residence

0:25:100:25:12

in my mouth over the last five days. It's hooked up to the microscope

0:25:120:25:16

and I'm looking at this stuff, I can actually see things wriggling about.

0:25:160:25:20

-What's that there?

-These long, slender, cigar-shaped rods

0:25:200:25:24

are probably fusobacterium.

0:25:240:25:27

We've got probably some streptococci here,

0:25:270:25:30

the round-shaped bacteria.

0:25:300:25:33

But we've also got some of these motile bacteria,

0:25:330:25:37

-likely to be spirochetes.

-It's a wonder I'm still alive!

0:25:370:25:42

-They're like little tadpoles swimming around.

-They are.

0:25:420:25:45

I thought I felt something in my mouth, I thought there was something odd going on!

0:25:450:25:50

-So, really, this is the cause of all of our problems, isn't it?

-It is.

0:25:500:25:54

That can lead to problems with your gums,

0:25:540:25:56

perhaps leading on to loose teeth and eventually tooth loss.

0:25:560:26:01

So the moral of the story is brush your teeth, I think?

0:26:010:26:03

-Brush your teeth well.

-OK, so there you go.

0:26:030:26:06

-Jem, teeth, fillings. Any fillings?

-Two, maybe three, actually.

0:26:060:26:11

-Liz?

-My dad's a dentist, so I'm a bit embarrassed to admit this,

0:26:110:26:14

-but it's three. Sorry, Dad.

-No fillings. Dentally perfect.

0:26:140:26:18

-Oh, for goodness' sake.

-Actually...

0:26:180:26:20

More worrying than that still, your VT suggested

0:26:200:26:24

that brushing your teeth immediately after eating sweets

0:26:240:26:28

-does more harm than good.

-If you think about it,

0:26:280:26:30

the acid is already eroding away at the enamel.

0:26:300:26:34

Add a toothbrush to that, you're aggravating the problem.

0:26:340:26:37

Ideally, you need to wait an hour between the sweet and the brushing.

0:26:370:26:41

See, that makes a lot of sense.

0:26:410:26:42

It's kind of counterintuitive but it makes a lot of sense.

0:26:420:26:45

Here's something for you. What is the best food to eat, for your teeth?

0:26:450:26:49

-What's the one food to eat?

-A massive toothpaste sandwich.

0:26:490:26:53

-Which makes a lot of sense.

-Or something that neutralises the acid.

0:26:530:26:57

The best food you can eat for your teeth is actually cheese.

0:26:570:27:00

It's full of calcium and phosphorus, good minerals for your teeth.

0:27:000:27:05

It's also alkaline so it helps neutralise the acid,

0:27:050:27:07

and if you use a strong cheese, like a vintage cheddar,

0:27:070:27:10

it produces lots of saliva, which helps fight tooth decay.

0:27:100:27:13

And there's plenty more about teeth at /bang.

0:27:130:27:16

Just follow the links to the Open University

0:27:160:27:19

where you can find out how teeth evolved.

0:27:190:27:22

And how doctors are using fluorescence to detect disease.

0:27:220:27:27

Next week, Dr Yan is messing around with radioactive waste.

0:27:270:27:31

You may be surprised to discover

0:27:310:27:33

just how radioactive some things are.

0:27:330:27:35

And I'm off to Amarillo in Texas to investigate

0:27:350:27:38

a potential global shortage of helium.

0:27:380:27:41

You may be thinking, "So what?", but there is more to helium

0:27:410:27:44

-that just making your voice go squeaky.

-All interesting stuff.

0:27:440:27:47

I'm also going to be checking out new airport security

0:27:470:27:50

that you're going to have to be dealing with on your next flight.

0:27:500:27:54

This device finds hidden weapons through your clothes.

0:27:540:27:57

Interested? That's coming up next week as well as a new BBC project

0:27:570:28:02

called 'So You Want To Be A Scientist.'

0:28:020:28:04

We're looking for budding amateur researchers.

0:28:040:28:07

More about that next week. See you then.

0:28:070:28:09

-Bye-bye.

-Bye-bye.

-Take care.

0:28:090:28:11

Subtitles by Red Bee Media Ltd

0:28:140:28:18

E-mail [email protected]

0:28:180:28:21

Dallas downs his toothbrush to discover what causes tooth decay and gum disease, Yan explains why refreezing food is not a great idea, and Jem investigates new research that electric lights can play havoc with the way we sleep.