What's That Rash? - Why do some people get motion sickness?

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0:29Norman SwanSo join me, Alicia Sivins. And me, Lee Bacha. Find it by searching for the dead kansu on ABC Listen, or wherever you get your podcasts. Norma, do you get motion sick? I do, actually. And certainly, although I do sail, if I'm a passenger in a sailing boat, I can get seasick, but not when I'm at the helm.

0:50Norman SwanInteresting, interesting. So that's more of a control freak. No, I'd argue it's different. Because if you understand motion sickness, when you're at the helm, you're really focusing on the horizon and the environment around you. And it's a bit more random when you're sitting. And so I think that's part of the reason. But is the control freak too? Yeah, no question. Well, really understanding motion sickness is what we are delivering to you today here on What's That Rash? The podcast where we answer the health questions that everybody's asking.

1:20Tegan TaylorWell, everybody's asking about motion sickness today, Norman. We had an email from Nat, who says, huge fan of the podcast. My question is, why do some people get motion sickness in cars or boats?

1:32Tegan TaylorAnd from Claire, who says, when I was a kid throughout my schooling years, I got terrible motion sickness and would often throw up on long car or bus trips. I was told that lots of kids got motion sickness and I'd eventually grow out of it. It's been a couple of decades since I finished school and I still haven't grown out of it. If anything, my motion sickness has become more sensitive. Why do some people grow out of motion sickness that others don't? At the age of 37, Claire says, I assume I'll never grow out of it, but it would be good to know why. So yes, what is motion sickness and does it change over our lifetime? What we'll cover today in this chat. We will. So motion sickness, I always assumed Norman that like biologically humans were never meant to go faster than we could run. So in the back of my mind, that's my very like

2:21Norman Swanrudimentary reason why we should get motion sickness, but I imagine that it's a little more complicated than that. Well, it's a little more complicated. We're probably close to something there. I mean, we can theorize forever on it, but yeah, we were...

2:33Norman SwanWe evolved to walk on the ground where we're in control. We didn't evolve to drive in a car or go on a boat. These are abnormal activities relative to human evolution. And as soon as you get onto a vehicle of some kind, you are in a situation where something else is moving against the horizon and your body is having to cope. I suppose we were, I don't know whether you get motion sickness on a horse or a camel.

3:00Norman SwanBut nonetheless... Usually you're too distracted by your terror of the fact that you're on a horse or a camel who overrides the motion sickness. I think you could probably get motion sickness on a camel. That sort of undulating thing. But you're right. We essentially evolved to walk by ourselves on the ground where we were in control and the horizon doesn't move. It's interesting you mentioned ships there and boats and floating, not being part of our sort of natural repertoire of movement. The word nausea actually comes from...

3:29Norman Swanthe same word that gives us the word nautical like it's from the same it's from it's from the word sea sickness yeah sea sickness comes from uh north as in ships sailing sailors it's the same route that gives us nautical so the two are very entwined at least in our language now this is going to have echoes of our yawning episode because i suspect that just talking about motion sickness it's going i'm getting it you're just going to feel a little bit yourself just stop spinning in your chair and it'll stop

3:56Tegan TaylorYeah, that's right. That's true, actually. I am in a spinning chair. Well, actually a spinning chair. Well, we'll come back to spinning chairs in another episode. Okay. Okay. So we're talking about motion sickness. Can we have a bit of an explanation of what is happening inside the body when you're moving and then you have nausea as a result? Well, first of all, this is an unpleasant condition. And you are in a situation where you're in motion, where you're not in control of that motion. It can either be

4:26Norman Swana real motion or your eyes can be foxed by a situation where you think you're in motion but you're actually not. Oh, people get it from VR, Google sometimes, like virtual reality. They can. They can get it in space travel. You can get it in electric vehicles where the silence of an electric vehicle doesn't give you an auditory cue that you are accelerating.

4:51Norman SwanI recently bought an electric vehicle and the guy who was selling it to us said, warned us about that and said, turn on, you know, some electric vehicles have this pseudo engine noise. And he said, turn on the engine noise and we find that the motion sickness feeling tends to go away because you've got that, he didn't say auditory cue, but that's what he was talking about. I'm not diminishing.

5:14Norman Swancar salesman here by not giving them the capacity to say auditory cue, but you know what I'm saying. So you're managing to be snobby and flex about the fact that you've got an EV now, Norman. No, no, no, no. So you've put on the noise in your car to stop yourself from feeling motion sick and its health. I never felt motion sickness to start with, but I put it on because I do miss the vroom-vroom of a petrol car. So now I've just gone from vroom-vroom to...

5:41Tegan TaylorAnd I haven't had any motion sickness. And what we're talking about here is that you feel nauseous, dizzy, you feel crap. You know, the technical term is malaise and you want to vomit and sometimes you do vomit. Okay. So there's this mismatch between the eyes and movement. That's the big one we've heard about before. You're saying there's maybe a bit of a mismatch between our learned auditory cues from traveling in combustion engine cars in the past and the movement. I think the word here is mismatch.

6:09Norman Swanand it's mismatched between several different sensory systems. And when your brain is in conflict, you start to get these symptoms of nausea, vomiting, dizziness, and malaise. And you can get that in other situations as well, but this is with motion where you're not in control of the motion. And it kind of has to do with what's happening inside our ears. Ears are not just for hearing, they're also really important for telling our...

6:35Norman Swanbrain where our body is in space and they can get confused. They do. So it's not the hearing part of your ears. In your inner ear you've got this canal system which is a bit like a gyroscope which go in different directions. There are right angles to each other and they've got hairs in them and they can detect acceleration and they can detect your position in space.

6:57Norman Swanand that's how you balance yourself. It's called the vestibular system and it's connected to parts of the brain which help to control that and your visual pathways are part of that process and your hearing is also related to it because your hearing is closely related to all this as well. So your core sensory system comes together in your vestibular system and it's also your joint position as well. So where your legs are in space, where your joints are, all this goes into the brain and gets integrated. And when there's a conflict between the two, the brain doesn't like it. Okay. It makes sense that you don't like it or that there's a mismatch there. Why is vomiting or wanting to vomit or feeling like you might vomit the symptom that you get though? Short answer is nobody knows. There is this toxin theory.

7:49Norman Swanfor motion sickness that the body behaves as if it's consumed a toxin. Oh, right. So like if you'd eaten something and it was your body's telling you to vomit, it's doing something similar. Yeah. I mean, these are theories to explain something that's hard to explain. Nonetheless, you go to crossover between systems here and there are neurological connections to things like the centers which induce vomiting. I mean, one of the questions we got was, why does it happen to some people and others? Do we know who's most at risk?

8:16Norman SwanWell, we do know that it is partly genetic. People have done what's called genome-wide association studies where you look at the pattern of what are called SNPs, single nucleotide polymorphisms. These are not mutations. This just shows the geography of your genome. And there are patterns of that which are associated with motion sickness. Explains why. You can have siblings in the same family. Some people who get it and some people don't.

8:43Norman SwanAnd the other issue with these genetic associations is that women do seem to suffer from motion sickness more than men. And some of these genes are more gender specific than others. But there's no easy explanation for why women might get more motion sickness than men or males, more than females. What about growing out of it? Is it something that you're more likely to have when you're younger? Well, there have been surveys looking at this through the years, looks as though Rare in infancy, although one of my children had it from infancy. A little baby would get on a plane and almost before the plane took off, she was vomiting. And that lasted throughout her childhood. She still gets a little bit of motion sickness. In fact, there's an argument in my family between my daughters about who gets to sit in front of the car. Because in the front of the car, you seem to get less motion sickness. But we'll come back to some of these solutions in a minute than in the back of the car.

9:38Norman Swanbut we do have paper bags available. I've got some horror stories to tell of trips and motion sickness, I have to say, including one episode where I had a hard car and didn't have time to clean it up, shut it and ran away to catch a plane, and then got a very large bill for cleaning afterwards. That's another story. But if you look at the data here, rather than my anecdotes, there seems to be, there's a U-shaped curve.

10:05Norman Swanwhere in childhood it seems to be high, seems to drop in adolescence, can go up again in later adolescence and then tends to go down again in adulthood. So Claire's pretty unlucky. A lot of adults do find it disappears or becomes less severe. So there is a post-puberty decline. On that, I wanted to talk about the idea of getting your sea legs or if you like to have a bit of fun on YouTube, you might have watched videos of like fighter pilots in

10:32Tegan Taylorflight school and they basically put them under incredible G-forces to see how much it takes for them to vomit or pass out or whatever. And obviously those people, it either weeds out people who aren't suited to it, maybe that's one way, or you somehow figure out how to inform your body that this is okay and like don't freak out and don't be nauseous and just deal with it. Is there sort of like a familiarization or a climatization process you can go through?

11:01Norman SwanWell, people think there is, and some people would swear by it. I think in space travel it's quite hard. And they talk about sea legs, getting your sea legs. If you talk to experienced sailors, they will admit that they still get seasick, slightly contradicts that it goes away after a while. I think that in the more extreme the situation you're in, almost anybody can experience motion sickness. So it's really unusual if you're in a small boat in a big sea, you're quite likely to get seasick. And there's probably nobody who's immune to it. It's really the severity of the motion and the motion disparity that causes it. So some people get it with a little bit of disparity and some people it requires a lot. But if you don't experience sailors or even fishermen, fishermen women, their boat might be in a river.

11:50Norman Swanand then they have to go out to sea, and it's a bit rough when they go out to sea, they will say that they get seasick during that first few minutes as they go out to sea, and then it settles. So a lot of people continue to get it. Now they learn how to want some ways of dealing with it. I think there's a little question. If you're at the helm, if you're a driver, you tend not to feel it because you prevent that mismatch between, say, the horizon, and the feeling of motion, so that your eyes are forced into a much closer coordination, because you are responsible for the directionality of the vessel or the car. And therefore, you are less likely to get motion sickness, whereas if you are not in that situation, your eyes are not forced to do it. But if you plant your feet on the deck and you focus on the horizon, you can tend to minimize, at least in the sea sickness sense, that feeling of sea sickness.

12:44Norman SwanI think they try to have all sorts of ways of doing it for space travel, but often in space travel they need medications to help them through. So I don't think that necessarily training gets you away from the fact that if you are in extreme situations, you will still feel it, but have little techniques for trying to minimize it. And some people will find that getting below deck helps, and some people will feel that getting above deck to the front of the boat, for example, makes a difference.

13:11Norman SwanAnd I've already spoken about the car, the front of the car, being the front seat seems to be less of a problem for emotional sickness than wallowing around and being teased by your brother.

13:20Tegan TaylorI can speak for my own experience. I love fresh air. So above deck, if I can be or crack a window in a car, although it is generally frowned upon to crack a window in a spacecraft. So I suppose we do need to have some other tools at disposal. What do we have? So if you've got severe and disabling motion sickness, there are treatments. So there are anti histamines. They mostly have an effect on the brain or thought to have an effect on the brain.

13:47Norman Swanor on the gastrointestinal system, making vomiting less likely. There's also drugs called scopolamine or hyacinth, those are the ones that you can put on the back of your ear on a patch, which actually interfere with nerve communication, how nerves communicate with each other. They can give you a dry mouth because they're atropine-like drugs. And there are the sort of drugs that anesthetists can give you before anesthetic to prevent vomiting when they're inducing an anesthetic. And then there are some new drugs that haven't necessarily been approved worldwide, which interfere with very specific brain pathways. So there are drugs which have an effect. And sometimes people have got to play around with those drugs to work out which ones help them best. So there's a bit of history here about using

14:40Tegan Taylorantihistamines and figuring out that there was a kind of side effect that was that it helped with motion sickness. There's a story from the 40s where this woman who had hives was going to the Johns Hopkins Allergy Clinic, but she had to ride the trolley. The clang-clang-clang went the clanger trolley to get to the clinic and she would get really nauseous on the trolley. And they gave her an antihistamine because she was there for hives. And when she was traveling home on the trolley, she didn't feel sick anymore. And so that sort of

15:08Norman Swansparked some research into antihistamines being helpful with motion sickness. I'm just wondering what the connection is between the mechanism of these drugs. We've spoken about this before. As soon as you find that a drug has an effect on a condition, usually by accident, then you launch medical research or theories to explain why.

15:29Norman SwanAnd I once did an interview with a researcher who found that a drug had an effect. It was a surprising effect. And I asked why. He said, I'm not interested in why. It just works. And, you know, any theory I'm going to give you is probably wrong. So they don't really know why, but they are effective. And it's just that antihistamine drugs have all sorts of effects on the nervous system, on the gut, on the sort of cells in your body that react to toxins, for example.

15:57Norman Swancomes back to that toxic theory that if it's simulating, you know, if it's imitating the reaction of a toxin, then antihistamines can help that. So there's lots of different reasons why antihistamine pills could help and there's probably several actions at once because they're kind of messy drugs. They have lots of different effects on the body.

16:15Tegan TaylorWell this, the timing of this particular episode was quite fortuitous because obviously it was the 40s as I said before and so they ended up turning into something that they called Operation Sea Sickness where when they had soldiers leaving to travel across the sea they put them into three different groups that got either this tablet before they went, this tablet on the journey if they got sea sick or a placebo and they did show that the tablet did make a difference in sea sickness. Unlike

16:43Norman Swanmany of the kind of remedies that are marketed to help with motion sickness and perhaps there isn't as much evidence for. Yeah, there's some evidence for ginger, particularly raw ginger. There are compounds there which speed stomach emptying and that may reduce nausea. So if you've got a full stomach when you get on a boat or a plane, nausea may translate into vomiting more easily. So ginger may well have an effect and certainly not going to do any harm to try that.

17:12Norman SwanAccupressure, so there are wrist bands that work by putting pressure on acupressure points. And if that does work, it's probably placebo. Mindfulness breathing has a physiological effect on the body and can be a distraction. Some people put rubber straps on the back of a car rubbing against the ground to remove the static inside the car.

17:32Tegan TaylorI think that's probably... Is that a thing? I remember seeing those... It used to be a thing. In the 90s, I think it was a thing. You'd see these cars with something trailing behind them, but... I've never seen a randomized trial of motor vehicles and straps, so... Fair. Norman, you've rattled off a lot of different remedies here, and it sounds like they have varying levels of evidence behind it. I would actually love to hear from folks, if you found something that works for you, because vibes-wise, Norman, that really seems to be the message here. If you figure out what works for you and just...

17:59Norman Swanignore the haters. Yes, send us your N of 1 studies in abortion sickness. We are all ears, all eyes, all feet. All vestibular systems. Yeah, we are on a stable ground ready to hear from you. So bottom line for Nat and Claire, who have sought us and our advice out. So Claire's probably got the genes. Sorry, Claire. But there are things that you can do to help yourself. But don't stop traveling. Have fun.

18:24Tegan Taylorif you're on a boat insist on taking the helm even if you don't know what you're doing and there are treatments. Well thank you Claire and that for your questions we love getting them. Our email address is thatrash at abc.net.au So what's in the mailbag? We had a chat recently about what you can do to reduce your cancer risk and a kind of Sobering question from Beck. Beck says, Thinking about this regarding my own cancer risk, is there a time that I can say that I'm no longer at risk of developing cancer related to passive smoking? Additionally, can I presume that the breast cancer I did have at age 42 when I had no predisposings factors myself was caused by passive smoking? It's a really good question back and it is sobering. So passive smoking in childhood and also

19:28Norman Swanpregnant women who might be exposed to passive smoke. Western Australian research has shown that it actually can change the lungs of the baby, of the fetus, in utero and increase the risk, for example, of asthma when the baby is born. So that's not just smoking in pregnancy. It's passive smoking in pregnancy, having an effect on the fetus. So passive smoking when you are exposed to it, particularly in childhood, but also in adulthood, the main risk is coronary heart disease. So the risk is not as high as smoking itself.

19:58Norman Swanbut it's there and significant. I, too, grew up with huge amounts of inhalation of passive smoking, and you do wonder what sort of effect it had on you. Now, let's assume there was a moment where your exposure to passive smoking disappeared. You'd have to extrapolate from smoking cessation itself in terms of the risk reduction. If you stop smoking cigarettes, your risk drops actually within hours of coronary events, sudden death, heart attack, those sorts of problems. Now, what's known from smoking cessation is that your cancer risk, particularly lung cancer, does decline, but it declines more slowly and never quite goes away. It would be impossible to say whether your breast cancer back at 42 was related to your passive smoking exposure.

20:54Tegan Taylorbecause that would be much less than smoking itself, but it was from an early age. So we can't really tell impossible to know. It's tricky with this cancer risk story because I feel like whatever we're talking about here, we're talking about dialing up or dialing down your risk, but you never get to 100%. You're definitely going to get cancer and you never get to zero. You'll never get cancer and you're only ever moving along a spectrum and you never get to know.

21:18Tegan Taylorwhere you actually sit or where you would have sat without that intervention. That's right. And you're doing the right thing, Beck. You've got a healthy lifestyle that's going to bring your cancer risk. Well done. All the best, Beck. Thanks so much for the email. You can send us your questions, your feedback, whatever you like. Our email address is that rash at abc.net.au. Before we go, this is a bit of a gear shift. But if you are a podcast lover, which I'm guessing you are, if you are listening to this.

21:43Norman SwanDid you know that your kids can also discover the joy of screen-free air entertainment, just the same as you? Indeed they can. All the best, funniest and, well, secretly educational. But don't tell them that. Podcasts are on ABC, listen. You can unearth adventures with Gardening Australia Junior. That's a really costar.

22:04Tegan TaylorExactly. Tiny Costa, Tiny Beard. Explore big questions with Imagine This and learn about the world with News Time. All of those shows and a whole lot more are available for free because it is ABC. And the ChildSafe part of ABC Listen, just look for the Kids tab. Are we in the ChildSafe part? I hope we are. I don't know if we're ChildSafe all the time, Norman. Anyway, while your kids is a busy, maybe you get to sneak in another episode of What's That Rash? So go on then. Look for the Kids tab in ABC Listen.

22:33Norman SwanAnd we'll see you next week. See you then.