Why does pain sometimes feel good?

This BBC podcast is supported by ads outside the UK. Hello, I'm Brian Cox. I'm Robin Ince and we're back for a new series of The Infinite Monkey Cage. We have our 201st extravaganza where we're going to talk about how animals emote when around trains and tunnels or something like that. I'm not entirely...

We're doing one on potatoes. Of course we're doing one on potatoes. You love potatoes. I know, but... Yeah, you love chips, you love mash. I'll only enjoy it if it's got curry sauce on it. We've always got techno fossils, moths versus butterflies, and a history of light. Listen on bbc.com or... wherever you get your podcasts. I've only actually done like the proper ice bathing once. And I was like, whoa, this is intensely painful.

We've got quite the sauna culture, and I have to say, plunging into freezing water when you're really hot is both pleasurable and painful. Sometimes when I get really super stressed... I sometimes enjoy eating really spicy foods. My tongue is like literally burning. Yeah, I'm kind of like feel that kind of strong experiences of the spiciness. kind of relieve my stress or probably pain can cure another pain

At the moment, I have a bilateral tennis elbow and an Achilles tendonitis. The reason being, I've got a one-year-old. So I'm now lifting this relatively heavy one-year-old kid all the time. So even though I'm in pain... I still do it because of the enjoyment or pleasure I get from seeing my one-year-old, you know, his smile and giggles. So that exceeds the pain that I'm experiencing from the tendonitis.

Pain is normally best avoided, but sometimes we can't escape it. And sometimes, as we just heard, we deliberately seek it out. Why is that? I'm Anand Jagatia, and in this episode of CrowdScience from the BBC World Service, we're exploring the fine line between pleasure and pain because of a question from listener Sandy. Hi, my name is Sandy and I live in Dubai. My question to CrowdScience is...

Why is it that certain unpleasant sensations and pain feel good? And what happens in the human mind when those sensations cross over from becoming something negative to something positive and even desirable? Nice. So basically the nub of it is why do we sometimes seem to enjoy or get pleasure from things which are normally, I guess, unpleasant or painful?

Absolutely. Yeah, 100 percent. And be that in all our senses, you know, I mean, whether it's like watching a horror movie or a gore film or or, you know, eating super spicy food or smelling some kind of skanky perfume or just being at the gym. hurting like hell, you know, these are all things that are technically supposed to be negative, but we sometimes find a lot of pleasure from it. And that's really what I'm interested in.

Yeah, it's such an intriguing idea. And I think it's something probably most people have got like something in their life that they do that is sort of on paper bad, but you kind of you like it. What's got you thinking about this? Well, initially it was because I'm really interested in perfumes. And at some point I had the chance to make my own perfumes and I started smelling some of the ingredients for these perfumes. And sometimes when I smell some of these...

They are absolutely disgusting. You know, they are horrifying, but they're yet used in perfumery. And I thought to myself, how is it that something that smells so disgusting can be used where somebody would buy it for like thousands of dollars and then, you know, wear a perfume of it? And then that got me thinking about... various other things like, you know, yeah, the spice in the food, for example.

Or the fact that, you know, maybe when we're young, something like beer, for example, would be so disgusting to us. But yet, when we pass a certain age and we get used to it, I mean, this is like our favorite drink of all time. And I was thinking, how does that brain kind of rewire itself? I mean, it's an interesting...

kind of question, you know. And I like how with your question, you're interested in the whole range of human sensation. So yeah, you know, the pain in your muscles from exercising, but also taste, smell. I mean... Do you have any potential theories as to what might be going on here? You know, I think a lot of it probably in my mind is...

I think it's social conditioning, like in the sense that, yeah, okay, there are some things that are not supposed to be positive, but yet you see that, you know, it's okay for everybody else and everybody else raves about it. And therefore you're like, okay, maybe this is good. But really other than that, like from a...

really physiological or biological person I really have no idea frankly well we will look into it I just hope that I don't have to do anything like unpleasant sometimes we get turned into guinea pigs on this show so i've got a bit of trepidation but yeah thank you sandy it's great to talk to you So why do we do things that don't feel particularly nice or even feel downright painful?

Do we enjoy certain sensations despite their unpleasant qualities? Or can discomfort in and of itself sometimes be pleasurable? Now, just to say there are lots of kinds of pain, like chronic pain, which are never pleasant. And also this is a family show, so there are limits to what we can discuss here.

But we're going to start with a kind of pain that people willingly administer to themselves all over the world. Chile. OK, should we try this Hellboy? It looks like one of those peppers where the pain builds rather than subside after a few minutes. This is Shahina Wasim, a.k.a. the UK chilli queen. Her life now revolves around eating some of the hottest chilli peppers in existence, ones that have words like death or hell in their names.

Shahina knows a thing or two about how painful these can be to consume. She's an undisputed champion of 97 chilli eating contests where people go head to head to see if they can handle the heat. Obviously when someone like that invites you round to their house, you know what's going to be on the menu.

It's a chocolate variety. A lot of people out there either hate chocolate peppers or love them. It's a really weird colour, isn't it? It looks almost like it's a really, really, really dark brown and really, really, really dark green.

combined so it looks kind of blackish or brownish but it's got this sort of luster under the skin hasn't it and it's quite wrinkly looks like it's got quite like a crisp exterior yeah but the wrinkled skin and and you know this like whole crumpled look like a piece of paper that's been crumpled together It's a giveaway, a dead giveaway of how hot this is going to be. Looking at the pepper, I'd say it's 1.5 to 2 million. So this one's definitely going to hurt.

The heat of chilli peppers is measured on something called the Scoville scale and those numbers are very high. Oh gosh, I'm not looking forward to this. This is interesting. OK. So if I cut that bit, then... Okay, so this is one you're cutting into the smallest pieces because it's going to be so hot. This is hot. If you like it, we can do more. Here we go. Okay, thank you, Sheena. Let's go for it.

Okay, I can tell immediately that this is, because it's not come yet, but it's building already. How are you getting on? So I ate that and I felt like there was like a hundred needles on my tongue straight away. Yeah, my tongue is sort of feeling, yeah, very sort of tingly, kind of like a stabby pain. I can feel my nose running. It's still getting, my mouth is still... getting i told you this was like a builder so this is gonna just keep building pain wise yeah

While the Hellboy pepper continues to destroy our mouths, let's take a closer look at what might be going on in our brains when we experience pain like this. Could that help explain why many of us like the feeling?

We've bought some spicy food and this has lots of lots of capsicines inside of the sauce so that it can induce really spiky and burning sensations on the people's tongues. This is Sue Ann Lee. She's a PhD student in biomedical engineering at Seungkyun Kwan University in South Korea. She's done experiments using capsaicin, the molecule that makes chilies hot, and sweet chocolate fluid.

She fed them to people through a tube to measure their responses to pain and pleasure while they were in an fMRI scanner, so she can see what's going on inside the brain. What we found was that inside of the brain... It has been recently shown that the brain regions that responded to the pain and pleasure has a big spatial overlaps, which means that the common brain regions show the responses to both pain and pleasure. So we found that the brain regions, including the...

amygdala, which is really famous for emotional processing for humans, and the insula as well, and the orbital frontal cortex. They were both responsive to the pain and pleasure. So we are kind of... think that, wow, this could be the common brain systems that represents the information of pain and pleasure. So my next question is, this might be a bit speculative on your part, but like...

Does the fact that there's overlap between brain systems involved in pain and pleasure, does that mean that there's overlap? potentially between the experiences of pain and pleasure? Like, are they kind of to an extent, two sides of the same coin?

Yeah. So probably we are kind of hypothesizing that inside of the brain, those common brain regions probably process the shared information between pain and pleasure, which could be like the... common scale, like, you know, the scale of the unpleasantness of the pain and pleasantness of the pleasure, and they're kind of competing with each other and to generate our subjective feelings about how...

positive or negative, our emotional states currently are. Yeah. Okay. So it kind of sounds like you're saying that maybe... there are these sort of two competing sort of ends of the scale that might be activated at the same time. And then possibly through analysing the signals from both sets, then you kind of figure out whether you like something or you don't like something or whether it's positive or negative. And maybe it's kind of...

both at the same time. Yeah, right, right. Given what we've talked about. What's your sort of take then on Sandy's question? You know, why we can sometimes be attracted to unpleasant or painful sensations? Can your research sort of shed any light on that question? Our like studies that doesn't really like directly like... test that kind of hypothesis. But I could say that probably we can get some hints about why we sometimes get addicted to the pain or negative events.

Our follow-up studies found that there were brain regions that specifically responded to the experience of pleasure after pain. not for the pleasure after pleasure. And those brain regions turned out to have a high density of the opioid receptors inside of the brain. So yeah, we're kind of like think that probably this... give us some hints about that the opioid systems probably plays a really important role about modulating the pleasantness or unpleasantness feelings of the pain and pleasure.

In other words, it looks like there might be something particularly rewarding about the pleasure you experience after pain that's different from the enjoyment you feel when you've already experienced pleasure. This research highlights that even though we think of pleasure and pain as opposites, they're intertwined. From your own experiences, you'll know that pain can reduce feelings of pleasure, and that pleasure can reduce feelings of pain.

According to Sue Ann, this interaction could be explained by common brain systems that process both, taking information about nice and not-so-nice stimuli to produce our current emotional state. Perhaps those brain regions that respond to pleasure after we've just experienced pain might help explain why we sometimes seek out things that hurt us.

Let's return to Shahina, the chilli queen, to get her perspective on self-inflicted pain. There's so many different... pains and experiences you're going to have. The first thing will be sweating and then tearing. The tears will fall from your eyes. You can't control them. A lot of people will get the shakes in their legs that you'll see their knees going, jerking up and down.

My mouth is on fire after just the tiniest sliver of the Hellboy chili, but Shahina has to eat multiple entire chilies in the contest she enters. As you sort of progress into a competition, the hotter they get, you do start to sort of get the hard burn. A lot of people will complain about it.

is burning, is feeling like they're on fire, which is something I experienced as well. And I always find it funny because there's always one ear or the other. It's never both. And it's one ear and it feels like it's just going to blow off like a rocket.

We had a question from one of our listeners who wants to know basically why as human beings sometimes we enjoy painful or unpleasant things. So what's your take on that question? Like for you... do you enjoy the pain or is it about just knowing that you can withstand something that you don't enjoy well i think like whenever you do these kind of extreme sports because i class chili eating as like an extreme sport pretty much you know there's so many different things

that come into play and both psychological and physiological responses of your body. Psychological in the sense that The admiration and the accolade that you receive. There's a whole community out there and people treat you like a hero. And physiological as well, like... I personally haven't ever experienced this, but a lot of people I speak with who do chili eating say they have an endorphin rush and they love it. It's like a drug almost. And that's why they eat hot food.

So I guess it's like both of those rewards there, in a sense of achievement like no other, that pushes people to do these things. For Shahina, the pain itself is far from enjoyable. But that's the whole point. She endures the agony to see how far she can push herself, and because she wants to win. The accolades and the prestige of victory are the reasons she's gone through this ordeal 97 times.

and doesn't show any sign of stopping. There's a social dimension to pain. People take pride in their ability to withstand it. But it's not just spicy foods that listener Sandy is interested in.

He also wondered why we like certain flavours that aren't exactly painful, but, well, just unpleasant. Like bitter flavours. So they smell great. I can't remember when the last time I actually ate a coffee bean and not drunk coffee. Now, bitterness is one of those things that doesn't seem like it should be very nice. And yet, dark chocolate, coffee and beer are three of the most delicious things I can think of. So what's going on?

Here to help is food scientist John Hayes, director of the Sensory Evaluation Centre at Pennsylvania State University in the US. If we think back to that lock and key model that you probably learned at one of your science classes somewhere in primary school of how enzymes work, about how things fit inside.

that lock and then you turn the key and then magic happens. Well, that's exactly what happens with taste. I spoke to him while eating the most bitter thing I could find in my house, coffee beans. It doesn't taste great, I'm gonna say. It kind of just tastes like mud or something.

So as you're chewing, your saliva is mixing with this, and there are some volatile chemicals in there that are actually going up through the back of your throat, and that's the coffee aroma that you're getting. And then there's also...

bitter chemicals that are dissolving in your saliva and then they're traveling through your taste buds into your taste buds on your tongue and activating these specific receptors that are causing nerves to fire that then carry the signal to your brain that say, okay, that's bitter. Why do we have bitter receptors? What's the advantage of us being able to detect bitter things? So the classic argument has always been that bitter equals toxic. And this is sort of the intro psychology framing.

of the worldview of evolutionary psychology is to say, well, we don't want to ingest those toxic compounds, so we evolve bitterness as a way to warn us. I personally don't believe that. My pet hypothesis is a variant on a theme. It's instead to say that I think bitterness tells us something is pharmacologically active.

So it could be that it's toxic and we avoid it, or it could be a sign that there's something interesting going on here. So maybe go slow and do a little bit of learning to make sure that it's not going to make you sick. There's something pharmacologically interesting, whether that be the anti-malarial properties of quinine or the bitterness of caffeine that's going to give you pharmacological benefits.

So as well as being maybe something that we should avoid, business is also something that maybe it's just useful to know about because we might be able to use it to our advantage. Absolutely. In fact, there's even work from non-human primates that shows that certain species of primates, when they're ill with certain parasites, will sneak out specific bitter leaves and ingest those and actually use that.

as a pharmacy to help clear them out of those parasites. And they only eat those plants when they're ill with those parasites. So the fact that it's not just humans that have figured out how to self-medicate using bitter plants. So bitterness can cut both ways. Sometimes we like it, sometimes we don't. And that makes sense. Bitter compounds could be toxic, but they could also have medicinal properties. Bitterness is like a signal for us to pay attention and we are incredibly sensitive to it.

There's not just one or two bitter receptors, there's actually 26 of them. And so we now know that there's one bitter gene that determines whether or not you find your... kale and your Brussels sprouts to be bitter. That's also the one responsible for whether or not you like hoppy IPAs. And then there's a separate bitter receptor that determines whether or not you're going to find things like stevia-based sweeteners.

to be bitter in those diet drinks. And then there's yet another one that determines whether you find things like saccharin bitter. So what this means is you may not like one diet cola. But then a totally different diet cola that uses a different sweetener, you might find perfectly fine based on differences in which specific repertoire of bitter receptor genes you have. You're listening to CrowdScience from the BBC World Service.

Hello, I'm Brian Cox. I'm Robin Ince and we're back for a new series of The Infinite Monkey Cage. We have our 201st extravaganza where we're going to talk about how animals emote when around trains and tunnels or something like that. I'm not entirely...

We're doing one on potatoes. Of course we're doing one on potatoes. You love potatoes. I know, but... Yeah, you love chips, you love mash. I'll only enjoy it if it's got curry sauce on it. We've always got techno fossils, moths versus butterflies, and a history of light. Listen on bbc.com or...

wherever you get your podcasts. I'm Anand Jagatia, and in this episode, we're trying to understand how negative sensations can nonetheless lead to positive experiences, thanks to a question from listener Sandy. We've just heard how variation in our genes might explain why some of us seem to enjoy I, for example, think that any chocolate above 80% cocoa tastes like eating a crayon, but other, presumably more refined people, appear to disagree.

Now, so far, we've looked at pain and pleasure when it comes to food, but Sandy was also curious about the pain of exercise. Many people enjoy feeling the burn from going out running, and there's even the rush of euphoria that's known as runner's high. So what causes the pain we feel when we break a sweat like this? And why might we enjoy it?

Hi, my name is Dr Robin Chatterjee and I work in various clinics in London and at the moment we're at the Institute of Sport and Exercise Health, which is in central London.

Robin is a consultant in musculoskeletal sport and exercise medicine. If we start off with hormonal responses to exercise that make... largely explain what's going on so there's a hormone called or a group of hormones called endorphins and they are released when we when we're exercising to capacity So there are different types of endorphins, and the one that's relevant for this conversation is known as beta endorphins.

It's released in response to stress, to pain or to strenuous exercise. So this is a natural... hormone that acts on the opiate receptors in the brain and that reduces pain so it's it's produced in response to pain so i mean the endorphins side of things is really interesting because it's like The same thing that your body is experiencing, so this exercise, this strain that is causing damage and making you feel pain.

you also have this series of mechanisms in your body that do the opposite and that make you feel less pain, make you feel happy, maybe calm your mood down. And so is that part of what's going on when people do exercise are experiencing pain, but then are also... experiencing something pleasant yeah so again when we exercise we can get pain for various reasons there's one mechanism of having pain is something called lactic acid build-up so whenever we do any kind of work or exercise

we require oxygen to deliver that work and if you're doing a certain type of exercise such as sprinting or I guess weightlifting, when we reach the threshold where we're getting in as much oxygen as we possibly can, where we don't have enough oxygen to do the work that we want to do, and that produces something called lactic acid. transition period can be painful.

But at the same time, we produce endorphins to counteract the pain and to give you a better sense of mood and well-being at the same time. And I think that natural high or natural rush is what makes people want to push. through that pain barrier. So running and other forms of exercise can trigger hormonal responses that cause us to feel good at the exact same time as our muscles are hurting from exertion. But Robin says that that on its own is actually a very narrow way of looking at pain.

I think in my early days as a doctor, I'd think of things physiologically and how to deal with it pharmacologically. But actually, pain is more multifactorial. So we need to think about the sort of psychosocial aspects of pain. psychosomatic aspects of pain mental health emotional aspects it's a complex thing

Pain can be a motivator for some people, or it can be considered a badge of honour by some people. Some individuals don't feel as though they've really exercised unless they're dripping in sweat. And similarly, others need to feel the burn. They need to feel that... You know, oh, I had a really good workout. My abdomen hurts from doing all those crunches. So it's pleasure because of pain, which I know sounds counterintuitive.

But actually, it's the trigger for doing more exercise to get that feeling of pain again. So we're now not talking about the runner's high, but we're talking about actual pain, so acute pain, which is spurring an individual on and making... When it comes to exercise, pain can literally initiate pleasure through endorphins that can help us push through. But there's more to think about here.

Pain can motivate us, validate us, even spur us on to greatness. For the most part, pain is something we avoid. It teaches us to steer clear of things that might harm us. But it's not always as clear cut as that. When our brains are deciding if something is painful or not, it turns out that context is really important. The thing is, we don't actually have pain receptors at all.

Well, we have these things called nociceptors and what they tell us about is the potential for danger. This is Siri Lechnes, a neuroscientist at the University of Oslo. Whether we interpret it as a pain or not depends entirely on the situation. So the same thing can be pleasurable in one context and painful in another. You know, we have the same thing in every situation, you know, it's like.

If you are really salt deprived, you will enjoy something super salty that would otherwise be disgusting. You know, if you've had too much chocolate, actually that can get kind of disgusting too, right? Weak. constantly interpret signals from the body and from the environment in relation to what we need at this time. And I think we tend to think that the body determines what.

what we need but actually you know so does the mind because we also need to experience things and we need to challenge ourselves and that's where the pain in a sort of you know fright in a sort of positive context comes in That's a really clever system. I mean, I'd always just assume that, yeah, you know, your pain system fires, then that's bad. But what you're saying is actually...

our brains are kind of interpreting what we may or may not need in different situations. And like, it's about the potential for pain. And so if you're having a massage, for example, if you're kind of expecting it to, you know, this is going to hurt, but it's going to be good for you, then it's sort of interpreted in a different way.

Yeah. And if you think something is good for you, it's definitely going to help with any pain. I mean, it's the same thing. We see the same thing with exercise, right? Like, you know, you wouldn't maybe tolerate that much unpleasantness if you didn't think it was useful. Pain signals can be ambiguous. They're something we interpret depending on the situation. Our response depends very much on our perspective, which means it isn't always a negative thing.

And in fact, looking at the bigger picture, feeling pain is part of what it means to be human. So there's a really nice notion put forward by an American psychologist, Erin Westgate, and some colleagues. They asked people what... they think is a good life? What should a good life contain? And they basically grouped people into three categories, the people who really just want pleasure or sort of, you know, a pleasant life.

The people who really want meaning. And then finally, a category of people who just want content. They just they want things to happen. They want their life to have ups and downs, presumably. I mean, I think that's really interesting that there's this sort of

broader, almost like philosophical view about what is a good life. And we've all heard this idea that, you know, you can't have the good without the bad. You can't have the pleasure without the pain on like a sort of, you know, idealistic level. But also, I suppose, on the level of actual sensation.

you know you can't get the beautiful view unless you gruelingly trek up the mountain and you know hurt your get blisters and all the rest of it so is part of this idea when we think about the pleasure of pain about the contrast that it is about that heightened sense of feeling the pleasure because of the presence of pain yeah well so there is some research suggesting that yeah pain can create a kind of contrast effect

But it also has this really interesting feature, which is that pain attracts attention into the body. That's a feature of pain, essentially. Something that could be a threat to you, you should probably pay attention to it. And that means, for instance, if you're eating a very hot curry, you'll literally be attending more to the meal. to the sensations in your mouth, presumably then also to the actual flavors. So you might enjoy the meal more simply because you're actually attending to it.

So you can enhance pleasure through the contrast of something you know trekking up the mountain but I think when you do you get the contrast but you also get the psychological sense of you having earned it. which can enhance the value on a different level.

Sandy, you asked us why we're attracted to some unpleasant or painful sensations. And the answer is that pain is nuanced. It isn't always a bad thing. Sometimes painful stimulation triggers hormones that make us feel good. Pain may also heighten pleasure by providing a contrast or focusing our attention. But even when it hurts, pain can have value.

It can teach us things, it can drive us forward, and it can give our lives meaning. Sandy, thanks for your question. It's been a pleasure, and only a little bit painful. Let's have the credits, please. That's it for this episode of Crowd Science from the BBC World Service. The question was for me, Sandy, in Dubai. The show was presented by Anand Jagatia and produced by Joe Glanville.

If you have a question on any science subject and you want the team to investigate, why not email crowdscience at bbc.co.uk. Goodbye. Hello, I'm Brian Cox. I'm Robin Ince and we're back for a new series of The Infinite Monkey Cage. We have our 201st extravaganza where we're going to talk about how animals emote when around trains and tunnels or something like that. I'm not entirely...

We're doing one on potatoes. Of course we're doing one on potatoes. You love potatoes. I know, but... Yeah, you love chips, you love mash. I'll only enjoy it if it's got curry sauce on it. We've always got techno fossils, moths versus butterflies, and a history of light. Listen on bbc.com or... wherever you get your podcasts.