Tonight on The Checkup ` the science behind cheese dreams. If you want to dream of celebrities, chew cheddar. Jayani makes no bones about osteoporosis. If your hip looks like that and you fall over, you'll bounce. And Sam finds out what happens to your blood donation. The filter's taking away all the white cells. But first ` the deadly consequences of driving while parched. (UPBEAT MUSIC) We all know mates don't let mates drive while drunk, but would you let a mate drive while thirsty? The dangers of driving under the influence of alcohol are well documented, but guess what? You could be driving accidentally while impaired because you haven't had enough H2O. In 2015, researchers at Loughborough University in the UK carried out a range of tests on male drivers. During the normal hydration test, there were 47 driving incidents. But when the men were dehydrated, that number more than doubled to 101. The errors included lane drifting, late breaking, and even crossing the centre line. All scary stuff,... (BRAKES SQUEAL) ...but easily rectified. As a rough guide, it's still agreed that adults should be aiming for six to eight glasses of fluid each day. And children ` four to six. But we're all unique, and so are our water needs. Weather conditions, physical activity and even those salty fish and chips you ate last night could have an effect. So how do you know if you're getting enough fluid? Normally, thirst is a reliable indicator that you need to drink up, but as well as focusing on what's going in, you need to take a look at what's coming out. The colour of your pee is the best proof of hydration health. Normally urine should be a light-coloured yellow. If it's a deeper or darker yellow, then it's likely you're not drinking enough fluid. Additional symptoms of dehydration include headaches, feeling weak and tired, feeling lightheaded or dizzy. That would explain the bad driving in the Loughborough experiment. The obvious solution is simply to down some liquid, bearing in mind water is more hydrating than high sugar, high calorie drinks. Avoid caffeinated and alcoholic beverages. These can make dehydration worse as you need to urinate more frequently. So keep an eye on your pee, and don't hit the road without a big tall drink of nature's finest. (FUNKY MUSIC) In our dairy-rich country, we Kiwis spend $6.5 million on cheese every week. Does that equate to millions of cheese dreams? It's a delicious source of protein and calcium, but can cheese really be the stuff of nightmares? (CREEPY MUSIC) The notion that cheese disrupts our sleep and causes nightmares is an old one. In Charles Dickens' 'A Christmas Carol', Scrooge blamed cheese for his ghostly nighttime encounters. And in a popular 1900's cartoon strip the main character regularly had strange dreams after eating Welsh rarebit, which is like a delicious kind of melted cheese on toast. (HORROR MUSIC) But can this harmless-looking Brie, Cheddar, or Edam be responsible for dreams where we fall off cliffs or find ourselves naked in front of a crowd? Why is cheese getting a bad rap? (SCARY MUSIC) Unfortunately, there is little scientific evidence that explores the link between cheese and nightmares in depth. The most common theory is that eating a lot of food, particularly rich food, before going to bed could give you indigestion. If this is the case, you may be more likely to wake up during the night, which increases the chances of remembering your dreams. In many countries, cheese is the last course of the night, so it may have got the blame by default. Scientifically speaking, though, the opposite could be true. Some cheese contains tryptophan, an amino acid the body uses to produce serotonin. Serotonin is a neurotransmitter that influences and improves sleep, cognition, and mood. This means that rather than disturbing our sleep, it could actually be aiding it. Cheese high five! One of the few studies tackling this cheese-dream connection was conducted by the British Cheese Board. The majority of its 200 participants reported having pleasant dreams after having a piece of cheese before bed. The Cheese Board telling us cheese is good is like... well, it's like getting a reference from your mum. She's only gonna say Gouda things. But the study got really interesting when participants were asked to report on the types of dreams they had after eating different varieties of cheese. Apparently, if you want a bizarre trip with visions of talking animals, vegetarian crocodiles, and warrior kittens, slice into the Stilton. If you want dreams about your favourite celebrities, chow down on the cheddar. And for a dreamless night, chew on the Cheshire. (PLAYFUL MUSIC) Dreams are certainly fascinating, but whether it's sweet dreams or nasty nightmares depends more on what's on your mind before you went to sleep, so don't blame the cheese. This is a highly magnified image of a piece of bone. Each year, we replace about a tenth of our skeleton, so over a decade, we completely rebuild our skeleton. You're preapproved for a secure Gem car loan, and you're still winding the windows down by hand. You won't miss out when you find the car you want, with approval before you buy and a rate from 9.99% fixed per annum. You can do better with Gem, powered by Latitude. Apply today. Garnier Fructis Hair Food - to nourish hungry hair. 98% natural, no parabens, with superfruits. Instantly absorbed with three ways to enjoy - as a conditioner, mask or leave in. For healthy hair, Garnier Fructis Hair Food. Choose yours. Garnier. * (SOFT PIANO MUSIC) 'Youth comes but once in a lifetime,' so said the poet Henry Wadsworth Longfellow. And with youth comes clear skin, bright eyes, and bones that have to last. In New Zealand, osteoporosis affects one in three women and one in five men over 50. The tricky thing about this disease is knowing if you have it. It's often referred to as a silent disease because until a bone unexpectedly breaks, like from a fall, or a knock, or even a sneeze, you won't know you've got it. So how do we make the most of what we're born with? Distinguished Professor Ian Reid is overturning age-old advice about how best to look after our bones. Do you think there are misconceptions about bones? Well, I think there probably are. I think a lot of people, including quite a few doctors, think that bone is about as interesting and dynamic as a piece of concrete. But it's not. Bones consist fundamentally of a framework that's made with a protein called collagen. And they're not solid like a piece of concrete, they're actually` the collagen is in an open meshwork, and then you have calcium and phosphate as mineral which is deposited as part of that meshwork. This is a highly magnified image of a piece of bone taken from the femoral head, which is right at the top of the thigh bone. You can fly right through, so you're getting a` sort of a blood cell's view of what the inside of bone looks like. That's amazing that we've got the technology to visualise and see what's happening with bones. Yeah. To show how dramatically our bones change as we get older, Ian has printed a pair of 3D models. This is a piece of bone from a healthy young individual who is strong and robust. And you can see it is an open meshwork, but it's a pretty robust meshwork. And when you hold it up, you can't actually see through it because the plates of bone overlap one another. And if you were to try and crush that, that would be moderately resistant. But if you take a piece of bone at exactly the same magnification from an older person who's bones are much thinner, may well have osteoporosis, then you can actually hold it up and look straight through it because a lot of the elements have been lost and the ones that remain are much thinner. And some of them, you can see, are just like tiny little bits of nylon fishing line; they're so fragile. And you wouldn't have to hit that very hard before that would completely give way. So, if your hip looks like that and you fall over, you'll bounce. If your hip looks like that and you fall over, you won't. It is possible to avoid such a dramatic decline. Whilst our bones stop growing in our late teens, they continue reforming throughout our lives. In the skeleton, we have cells that are there all the time working away, taking away little packets of old tacky bone that's eight or 10 years old. And other packets of bone-forming cells that are replacing the bone that's being taken away. And so each year, we replace about a tenth of our skeleton. So, over a decade, we completely rebuild our skeleton. Keeping our bones strong is a balancing act. The amount of bone forming needs to counteract what's being broken down. How do you keep your bones nice and healthy? By eating lots of food. With milk. Why is milk good for your bones? Because it has calcium in it, and your bones are made out of calcium. These guys are right on the money. While our bones are still growing, we need plenty of calcium. 1.3 grams a day in our teenage years. Milk and dairy products are a good source, but so are sardines, green leafy vegetables, legumes, nuts and seeds. So we know that calcium is important for our bones, but what does it actually do? Well, it's one of the building blocks of bone, but it's only one of them. We need calcium, we need phosphate, and we need a good supply of protein to grow healthy bones. So you need a balanced diet. Ian's research has knocked down the long-standing idea that in adults more calcium means stronger bones. How much calcium should we be getting as an adult? That's controversial, and you'll get different answers from different people. So historically in Africa and Asia, calcium intakes have been 200mg to 300mg a day. And a lot of Western bone experts have been saying for many decades that's quite inadequate. But the reality is that fracture rates in traditionally living African and Asian populations have typically been lower than in the West. Ian believes that most people are already getting enough calcium in their everyday diet. But to make sure it's absorbed, we must get out in the sun. What does vitamin D do for our bones? So vitamin D is not a vitamin; it's actually a substance we make in our own skin when we expose our skin to sunshine. And it's important for allowing our bodies to absorb both calcium and phosphate from the diet. The recommendations that have been put together in Australia and New Zealand suggest that in the middle of summer, you should try and get perhaps 10 or 20 minutes of sunshine exposure a day, but not in the middle of the day. Take it in the early morning and the late afternoon. In the middle of winter, the sun is obviously much weaker, and so you can spend half an hour in the middle of the day. Between the ages of 20 and 60, a balanced diet, regular sunshine, and high-impact exercise can keep our bone formation in balance with absorption. But when women hit menopause, and men reach their mid-70s, the balance naturally tips towards more loss. So if someone has osteoporosis, what can we do about it? Well, there are a variety of treatments. We can reset the balance between the bone-forming cells and the bone-absorbing cells, and when we do that over a period of a couple of years, we reduce the number of fractures by a third to a half. Unfortunately, there's no quick fix for osteoporosis, but it is reassuring to know that I'm getting enough calcium and vitamin D to tip the balance in my favour. (ALL LAUGH) One whole blood can be separated into three components. So one donation has the ability to save three lives. So what do you think contributes towards acne? Greasy doughnuts. (LAUGHS) * The New Zealand Blood Service depends on 3000 donations every single week to keep the country's supplies stocked up. The Kiwis who give up their time and precious blood are superheroes. Lifesavers ` literally. But what does it take to earn your cape? Hello, Don. Hello. Nice to meet you. And you too. Why are you giving blood? Well, everybody should give blood, I think. I think because it's so easy to do, and it has such a big impact on people that need it. How long does it take? With the needle in, oh, I can do it in about five, maybe six minutes. It's not very long at all. Super fast. Super fast, yeah. I'm lucky there. The time it takes varies from person to person, but on average, you're looking at only five to 10 minutes to donate and 20 minutes and a bikkie to bounce back. If you can't give an hour and a half a year to save a few lives, well, what can you do? Most people can give blood, but a nurse will go through a confidential questionnaire with you to check you're eligible to donate. Don's just given what's called a whole blood donation, where a needle's popped into his vein and 470mls of blood are taken, and then it's all done. Whole blood donations are the most popular, but by no means the only type of donations needed. Hi, Paul. Hello. Paul is a plasma donor. So, I understand you're up to a large number of donations? Yeah, I have 587. Wow! So what I can see is that the blood comes out of your vein, down these tubes, up into the centrifuge machine. Yeah, it spins the plasma off. And so this is the plasma? Yep. The gold liquid. The gold stuff. Yeah. Plasma makes up over half of our blood. It's made up of proteins, water, and clotting factors. As the machine draws out the plasma, the rest of Paul's blood gets returned to his body. With the donor's job done, what becomes of these bags of life-saving liquid? (UPBEAT KEYBOARD MUSIC) Ron is in charge of processing the whole blood donations. Scanning them into the system? Yes, it's all tracked. They still feel warm. Well, they are because they've just come out of the donor, really. (UPBEAT MUSIC) So we're putting the blood into the centrifuge? Yes. A centrifuge works like the spin cycle on your washing machine. The centrifugation will separate the components in the blood by its density. So the red cells will be at the bottom and the plasmas will be at the top. Once the whole blood donation is broken down, it's time to isolate the different components. So the plasma, the red cells, and the thin layer of buffy coats` Where the platelets are. Where the platelets and the white cells are. OK. So, this machine knows how much plasma to push out, and how much red cells to push out. The plasma's been expressed to the bag connected to the top. The red cells are being expressed to the bag that's connected to the bottom of the bag. So one whole blood component, we can separate into three components. So one donation has the ability to save three lives. However, before the red cells are used, the white cells within it have to be removed. This is a white cell filter. We remove the white cells because the white cells have the ability to cause transfusion reactions. So this is the process of leucodepletion. So, the red cells are going through this filter, and the filter's taking away all the white cells. It makes it safer for people when they're having blood that they don't have a reaction to it. That's right. It reduces the complications. Once filtered and tested for disease, the red blood cells are stored until they are transported for use. They are used to treat all kinds of anaemias and are vital in emergencies or surgery where there is heavy blood loss. Platelets are crucial in helping blood to clot. They are used after transplants or chemotherapy to treat leukaemias and some blood diseases. To prevent the platelets clotting, they are stored in a machine that keeps them constantly moving. The plasma component of the blood is used for clotting deficiencies and auto-immune disorders. After processing, some of the donated plasma goes directly to our hospitals and the rest heads to Australia. It's purified, concentrated, and then made into 13 blood products ready for medical use back here in New Zealand. It comes back to us as a finished product. And this is what goes to the hospitals to be used on patients? Yes. So it's a jet-set plasma. (BOTH LAUGH) Yeah, so to speak. International traveller. Yep. What's the advantage of getting people to donate plasma versus people donating whole blood? Well, when we collect plasma, we get a 700ml unit from one donation. Of plasma? Of plasma. And if you were trying to achieve the same thing with whole blood donations, you'd probably need about two or three whole blood donations to achieve the same result. Plasma donors are in high demand, so if you have an hour to spare and meet the criteria, one bag of your liquid gold could go a long way. It's been fascinating to see all the hard work that goes on behind the scenes not only to prepare blood for transfusions, but to create blood products that help people with all sorts of medical conditions. (FUNKY MUSIC) (PLAYFUL MUSIC) Some people love squeezing zits. Online groups are devoted to it, and toys recreate it, but it's not a game for those suffering from acne. Blackheads, whiteheads, and pimples all come under the dreaded acne umbrella and can make an unwanted appearance no matter what age you are. So, what do you think contributes towards acne? Well, I know from my personal experience, it's hereditary. Oh, the food you eat. Yep. And the... cosmetic usage. Bad food. And we have lots of it around here. And what types of bad food? The yummy ones. (LAUGHS) My personal ones ` too much dairy. Dairy. A lot of dairy will overdo it. And chocolate. Greasy steak, sausages, greasy doughnuts. Greasy doughnuts. (LAUGHS) Acne occurs when glands in your hair follicles produce too much oil. When dead skin cells mix with the oil, a plug forms. Acne bacteria grow in this trapped oil and cause inflammation. The most commonly afflicted are girls aged 14 to 17 and boys aged 16 to 19. Hello. Hi. How are you? Good. How are you? Good, thank you. Hey, can I order some hot chips, please? Sure. It's $3. Thank you. Thank you. Yeah, awesome. Thank you so much. Cheers. Bye-bye. The reason that teenagers have it so rough is that hormones can increase the size and oil production of these glands. Prime targets are your face, forehead, chest, upper back and shoulders because they have the most oil glands. And what impact does diet have? Your skin won't make zit-causing oil just because you indulge in greasy food, but annoyingly for hot chip lovers, there's evidence that high GI foods may promote acne. That's because foods with a high glycaemic level cause blood glucose to rise rapidly, and high levels of blood insulin are thought to encourage acne. Unfortunately, the sugar in chocolate raises these levels. Dairy products have also been found to increase the prevalence of acne, and what is chocolate made of? Larger trials are needed to fully understand the link between food and acne, but recent studies suggest that a low GI diet may reduce its severity. Most fruit and veg are low GI, so are oats, legumes and pasta. Buon appetito! Over 80% of teenagers can experience acne, but that could all change in the future. How does an acne vaccine sound? Researchers are on the case. Captions by Lillie Balfour. Edited by Antony Vlug. Captions were made with the support of NZ On Air.