Tonight on 20/20... It doesn't feel good. It doesn't feel healthy, because it's not. Fifty shades... of grey matter. So what are we talking about? Every day? So what are we talking about? Every day? Yeah. Two or three times a day. Brain trauma put their sex drives in overdrive. You got sick of sex? Then... It's something I can't talk about. Battling the compulsion... It's something I can't stop. ...to pull out her own hair. Pulling makes me feel better. They thought I was crazy. The phobia controlling her life. The fear just engulfs, and it swallows everything around you. Can she overcome her fear... Just make myself throw up. ...of vomiting? I can't do it. (SOBS) Kia ora. I'm Sonya Wilson. It's a strange affliction ` hyper-sexuality; a desire for sex all the time, even though you might not enjoy it, even at the expense of your relationship. For two women, a brain injury changed them incredibly. Happily married, Heather awoke from a coma, and her husband quickly realised she was no longer the person he'd married. She was pursuing other men, sometimes offering sex within seconds. And then there's Allyssa. After a car crash, she left hospital with a new sexual compulsion, and as you'll see, it's a tough one to manage. This is Allyssa. Just Allyssa. No last names. It's that kind of a story. She's 23, single, lives in Vancouver. Behind that bold, blue eyeshadow ` an ordinary woman with a strange tale of desire gone wild. Did you ever imagine that car accident could so change the course of your life? I think that, as people, we'd like to think that our personality is a bit more stable. And this is Heather, happily ` and normally faithfully ` married to her husband, Andy. They're from England. She too has a story that would make just about anyone blush. Walking down the street, for a while, was hazardous. She'd catch people's attention ` guys. She'd just give them a look. I was never subtle with it. I was never subtle with it. You were never subtle? I was never subtle with it. You were never subtle? No. It wasn't a 'come hither' look, it was a 'come...' It wasn't a 'come hither' look, it was a 'come...' Yeah. 'Get it' look. Two women a world apart with one thing in common ` a brain injury that transformed them in ways both intimate and unimaginable; trauma, through a switch in their brains, supercharging their sex drive. Their story might be called Fifty Shades of Grey Matter. I think I was doing some gardening that day, and I collapsed in the garden. And I can remember a huge pressure in my head and knowing that something was really wrong. Heather's X-rated odyssey begins with a subarachnoid haemorrhage ` massive bleeding in her brain. It left her in a coma for two weeks. Doctors were not hopeful. They said, 'It's not good. She's probably not going to survive.' During our interview, a moment of brutal frankness that shocks Heather. He tells us, in a way, he did lose his wife. The wife that I married died on May 21st 2005. The wife that I married died on May 21st 2005. Don't say that. It's really sad. It's true, though. It's true, though. It's not. It's true, though. It's not. That's what happened. Heather emerges from the coma with a voracious interest in sex, starting in the hospital. So, she wanted to have sex with you in the hospital bathroom? So, she wanted to have sex with you in the hospital bathroom? Yeah. In the shower room. While she was still hospitalised? While she was still hospitalised? Yeah. After she was released, it only got better, that is to say, worse. So what are we talking about? Every day? Yeah. Two or three times a day. Yeah. Two or three times a day. Two or three times a day? It was emotionally hard. It was physically hard. It was hard. It was hard. You got sick of sex? Not sick of it, but, um, just, sort of, bored of the frequency of it. And then one day as Andy watches, Heather crosses the street from their home to pick up a construction worker. This guy called her over, and she goes. When she got to the doorway, he kissed her on her mouth, and I was watching. She crossed the street, and she's making out with a man? I'm just watching, thinking, 'What's happening now?' Heather begins propositioning and groping other men, left and right. She'd meet people, and within seconds, she'd be offering them sex or even having sex with them. You look like such a demure, sweet, young lady. Truly. You look like such a demure, sweet, young lady. Truly. I am. It's hard to even imagine you doing all of these things. < Is it just an urge to have sex? < Is it just an urge to have sex? I think so. Experts say brain trauma often causes a decrease in libido. Only rarely does it cause the opposite; what doctors call hyper-sexuality. Heather and Andy met with Harvard neurologist Dr Alice Flaherty as part of a British documentary. These things here are your temporal lobes, and a lot of this is what was damaged when I looked at your CT. This is where the aneurysm` the blood squirted out and hit this the most, and also causing damage to the hypothalamus, which is there, right in the centre of the brain. Right at the front of it is the amygdala. It's very important for fear, and I think you're more fearless. You're able to approach things and do things that you wouldn't before. Andy estimates Heather had sex with about 10 other men, but behaved inappropriately with as many as 50. Heather, at the time, couldn't see that there was anything, sort of, out of the ordinary. She didn't think she was doing anything wrong. She was, like, 'Oh, why can't I?' Didn't matter how old they were, didn't matter how handsome they were, didn't matter how fit they were? It just mattered that it was a man. Yeah. Yeah. Yeah. Yeah. It wasn't about the guys; it was about her. It's like a sport. You know, going out and seeing if there was... It's like a sport. You know, going out and seeing if there was... ...anybody around. Yeah. In Vancouver, Allyssa is also trying to manage a new sexual personality, which she traces to a car crash in 2008. The car flipped over three times. I hit my head. And the next time I woke up was in the morning, in the hospital. She had been a typical teenager, she says, interested in fashion and sewing. Her experimentation was mostly confined to hair colour. So you weren't boy crazy, as they say. So you weren't boy crazy, as they say. Basically, yeah. And you'd had, basically, one sexual experience. And you'd had, basically, one sexual experience. Yeah, with one guy beforehand. But from this crumpled wreckage, Allyssa says she emerged a changed person. So what did you begin to notice about yourself? I was tired. I was depressed. Anxiety. I was withdrawn socially. The area of her brain injured in the crash was the frontal lobe, the part that controls impulses. Everything needs a braking system. Everything needs some sort of control. And when there's none, it's usually a disaster. That brake failure led to Allyssa's strangest affliction. How much of your thoughts after this brain injury were taken up with sex? There was definitely much of the day. Scott Stanley is Allyssa's attorney. Before the accident, she was just a normal kid, and then afterwards she would use this expressly explicit language detailing sex, and would say things that would just cause people to shudder. This had to be such a big dramatic difference to be not very interested in sex and then all of a sudden, obsessed with sex. Did you suspect it was because of the brain injury? I think at first I just blamed myself. I just felt a lot of shame. Allyssa says she couldn't stop herself, but she couldn't enjoy herself either. I don't necessarily, physically, actually, enjoy sex all that much. I'm doing it to satisfy a compulsion. It doesn't feel good. It doesn't feel healthy, because it's not. Making a virtue of a vice, Allyssa now sells provocative videos of herself under an alter-ego ` Sasha Misery. Listen to my voice. Her sexual compulsion was cited by her lawyer as part of a lawsuit against the driver responsible for her accident. The judge awarded her $1.5 million. The judge agreed with us that her increased sexual activity, her sexual impulsivity flowed from her frontal-lobe brain injury. She's in therapy and on medication, and says just recently her sexual urges have begun to diminish. So now you're not at a point where every waking thought is about sex? So now you're not at a point where every waking thought is about sex? Right now, knock on wood, no. What she really wants now, she says, is someone to love. Heather and Andy's outcome may give Alyssa some hope. Heather's desire has been dampened by therapy and prescription drugs, sort of a pharmaceutical cold shower for her overheated libido. Do you still have those urges or are you just better at controlling them? I don't think I have them so much at all now. I also make sure I'm not in a situation where there's only me and a bloke, you know. I just make sure that that never happens, really. They're now celebrating more than 20 years of a marriage that truly tested nearly every vow. Up next, we meet the 'trichster'. She's called Becky O and has a hair-pulling disorder. Pulling makes me feel better. But when you see the damage afterwards, then you think, 'Oh no, OK.' I can just pull out yanks of hair. I've got hair surrounding the keyboard. Are you sick of feeling sick? Ever find it hard remembering last night? Are your loved ones over your drinking? If you're answering 'yeah' a bit too much, maybe we can help you say 'nah'. Welcome back. 16-year-old Becky O went viral when she disclosed her most closely held secret to thousands of fans on her You Tube channel. She's a 'trichster' suffering from a hair-pulling disorder. Becky has been documenting her disorder for years, and shared her experience with us here at 20/20. Hello, everyone. (EXHALES) # Prom. # Ooh, aaahh! Welcome to the high-octane technicolour world of Becky O. Here we go. Long story. Hold on. Hello. Those quirky antics won her thousands of You Tube fans. But what blasted Becky O to fame, was going public with the most private of secrets. This is something I can't talk about. I've tried everything, and nothing seems to stop it. She, like 10 million Americans, suffers from a compulsion to pull out her own hair. It's something I can't stop. That video just exploded. It had hundreds of thousands of views. It just` It really opened my eyes to how big the condition was. You didn't know anybody else who pulled their hair? Nobody at all. I thought I was on my own. For Rebecca, it's tough living in a culture obsessed by hair, surrounded by women crowned with long, shining locks. So she took her battle to the internet, blogging about her struggle with the disorder called trichotillomania. Literally, the mania to pull out hair. She calls herself a 'trichster'. So, is it a relief or a release to pull? Pulling makes me feel better. But when you see the damage afterwards, then you think, 'Oh no. OK. That's making me feel worse.' You would have a bald spot the size of your fist? Yeah. This is the most hair I've had in five years. And that terrifies me. Why does it terrify you? Why does it terrify you? Because I'm always worried I'm gonna lose it. As a child she often played with her hair but the vlogs of her teenage years reveal a habit spinning dangerously out of control. I can just pull out yanks of hair. I've got hair surrounding the keyboard. I remember when I was 12, and I was with a counsellor, and she said to me, 'When you're stressed, where do you feel it in your body?' I remember my answer. I remember holding my hands up and going, 'In my fingers.' It's-It's here. It's not here; it's here. It's not here; it's here. It's here. I want to do things with my hands. Most weirdest thing about pulling is it feels like my fingers are magnets and they're attracted to certain parts of my head. Nothing could keep Rebecca's fingers from pulling her hair; not tying her hair up in a turban or greasing her eyelashes and eyebrows with Vaseline. Even the most extreme measures failed to help. I found just tying my hands to tables or chair legs or to my tummy when I was at school would stop me from getting to the hair. So that you wouldn't reach up and pull your hair? You get to a point where you're so desperate. That desperation was often driven by the hurtful comments from her peers at school. If I had the hair, if I didn't have this, some people wouldn't have treated me so badly. Worst of all was the criticism from friends and even family members, which she repeated in her vlogs. 'You'll never get a job looking like that.' 'Don't you realise you're doing it to yourself?' 'Looks like someone went too far with the tweezers.' 'No one wants a bald girlfriend.' There were a lot of really... Yeah, every single thing... Yeah, every single thing... ...harsh comments. Trichsters receive such severe backlash. Why is that, do you think? Why is that, do you think? I think people don't appreciate that you literally cannot stop. It's not even a choice. I can't leave it alone. It had been a six-year roller coaster of frustration, documented in this astonishing video diary. On the 3rd of February 2011 I decided to shave all my hair off. When I shaved my hair, I thought, 'Right, that's it. The hair's gone. I'm not going to pull again. 'It's all good.' But then I attacked my eyebrows and they vanished within a week. I have always loved cameras. Oh, and the colour pink. Rebecca, now a superstar in the trichster community, caught the attention of Jillian Corsie. She was casting for a documentary on trichotillomania. What's the biggest misconception? That it's rare. That people who have trichotillomania are freaks. The people who I've spoken to feel isolated or like outcasts, like they don't belong. Jillian's documentary Trichster explored the destructive force of the disorder to both mind and body. Kinda feel like putting the wig back on. Unlike most trichsters in the documentary, Sophie Ehrmann pulled hair not from her head, but from her body. The difference between me and a lot of people that just have trich, I'm digging under my skin. Sophie's a photographer and documented her struggle with trichotillomania in a series of disturbing photos. To her, each tiny hair in a leg is a monstrous flaw. What is this? What is this? This is literally how close I look at my body. Those are, like, hairs that are, like, literally growing. It's gross. I don't like the hair on my body, so... Any of it? Any of it? No. None of it. I'd rather just be like a baby. So in this effort to get rid of these hairs you think you see growing, you're essentially gouging at your own skin. Right. Right. < And making it... Right. < And making it... ...worse. So if you were to take your tights off for me today, where on your legs would you have scars? Like, everywhere. She showed me the raw wounds that force her to hide in tights and jeans, even on the hottest days of summer. See, like, how there are all these dots? < Yeah? < Yeah? So those are the hairs. There must be a lot of people who cannot understand why you're doing this to yourself. Join the crowd. Like, I don't really know exactly what I'm doing to myself. I know that I'm doing it to relieve anxiety, but what made me choose to pull out my hair? I have no clue. The cause of trichotillomania is still a mystery, and doctors are still baffled about why it's primarily women who suffer from it. Sophie and Rebecca both doubt they will ever be pull-free. Do I want to stop? Absolutely. Can I? I... don't know. Do you ever think you'll stop doing this pulling? No. No. Really? I feel I will be pulling till the day I die. I've been doing it for 20 years. I dunno. But it's part of me. Rebecca may never have that long, blonde hair that she dreams of, but she's learned to love what she does have, and for now, better control the urge to pull. There was a point I remember when, for the first time in years, I felt the wind go through my hair, and it just pushed my fringe back, and I was, like, 'Oh, wow.' Like, whoosh! Happiness! After the break, can she overcome her phobia of vomiting to make it down the aisle? (CRIES) The goal is all of the anxiety that comes with throwing up. I want all of that to come out. I know you're trying hard. You don't have to say anything. Welcome back. Jessica Mellen is one of more than 40 million Americans who suffer from anxiety disorder. Her most intense fear, the one that completely devastates her and brings her life to a halt, is the fear of vomiting. Wanting to marry the man she loves, Jessica has decided to put herself through exposure therapy, but will it work? If someone's like, 'You can either be shot in the leg or you can throw up once,' I would be like, 'Yeah, shoot me in the leg.' I would really pick that. You would choose being shot in the leg? You would choose being shot in the leg? Absolutely. 'Jessica is intensely afraid of vomiting.' To me, that's one of the worst things that could happen to me, if not the worst. It's called emetophobia, and millions of people have it. I didn't know that there were other people like me suffering from this. I didn't know that there were other people like me suffering from this. A lot of people like you. Jessica's entire life was choreographed around protecting herself against the possibility of throwing up; taking every precaution against catching the flu from co-workers,... I would be, like, 'Are you very sick? Is it a stomach thing? Is it something you ate?' ...to the pharmacy in her purse, armouring her against throwing up ` antacids, tummy drops, cough drops, hand sanitizer. You take one of these tablets twice a day. Do you ever feel frustrated... Do you ever feel frustrated... Absolutely. ...that you were this out of control? The fear just engulfs, and it swallows everything around you. Everything, even the lifelong dream she and her fiance share. I've never been this scared in my entire life, I don't think. Jessica is so terrified of getting morning sickness, she's told the man she loves she won't get pregnant. And that's putting the most important relationship in her life at risk. You know how extreme that is,... Yeah. Yeah. ...to give up bringing your own baby, another life into this world, simply because you're afraid you might have morning sickness and throw up? I know. (CHUCKLES AWKWARDLY) Sorry. I know. (CHUCKLES AWKWARDLY) Sorry. That's OK. Why are you crying? I don't want to miss out on something that could be really special between the two of us because of my phobia. It's not fair to him either. But right now you simply can't? But right now you simply can't? Uh-uh. I can't. Marvin and Jessica met and fell in love while working at a restaurant they own together in Philadelphia. We just automatically clicked right off the bat. Everything was going well until they started planning a wedding and a family. How fraught did your relationship get as a result? I told him that if he felt like he couldn't continue with this relationship because I might not be able to do this that... obviously, I would be devastated, but I would have to let him go. I'm scared, like, if I can't get to this point where I feel like I'm OK to get pregnant, like what that's going to mean for us in our relationship. Jess, uh,... it's not ideal, OK, but, like, neither are a lot of things in life. In the beginning, did you think it was funny. Like, 'Are you kidding?' I just thought that, 'You're not willing to even risk throwing up to have a kid with me?' I mean, I took offence to it. Desperate to conquer her phobia, she choses a radical path. The treatment we are allowed to tape is rarely shown on camera. Her doctor is Steven Tsao. We have to be deliberate. Let's confront this and let's really confront it. Dr Tsao is talking about exposure therapy. He's throwing up into a toilet. The goal is to desensitise Jessica to her fears by directly confronting them. It's like I can smell it. Suddenly her eyes fill with tears as a memory she's repressed surfaces. I think I'm starting to remember why I'm so scared of it, which is making me really upset. The last time I got sick when I was younger, I threw up so bad I couldn't breathe, and it was really scary. It's the first major step toward learning to control her phobia. You should be really proud of yourself. You should be really proud of yourself. Thank you. Over the next five months, the attack is relentless and targeted; from pictures of people throwing up to eating food she thinks is unsafe and will make her sick. Time and again, he forces Jessica past her comfort zone. But with just weeks now until her wedding day, Jessica's still not sure whether she's ready to get married, because she's still afraid of getting pregnant I can't have a child until I feel better about this. I'm tempted to just make myself throw up. Jessica is horrified when Dr Tsao asks her to do exactly that at their next session. Is it this one or is it...? Is it this one or is it...? No, it's the next one. Is it this one or is it...? No, it's the next one. The next one. OK. Down this hall and into the claustrophobic confines of a tiny bathroom, Jessica is about to take a leap of faith. (CRIES) But after an hour and a half of tears and frustration... (COUGHS, SOBS) I can't do it. She may feel defeated, but the goal was never about actually throwing up. The goal is all of the anxiety that comes with throwing up. I want all of that to come out. I know you're trying hard. You don't have to say anything. Marvin still hopes she will someday have his baby, but for now, he is willing to wait. The more and more I realise that she is actually, like, deathly afraid to throw up, the more it becomes, like, real for us, you know. The therapy has helped Jessica a little and helped Marvin understand a lot, and so the reward of those five brutal months came on a beautiful fall afternoon. Anxiety was only a brief guest at the wedding. What happened when you waited there in that gorgeous dress of yours? The anxiety started to climb, started to increase cos, 'My turn's coming up. My turn's coming up.' My mom walked me down the aisle, and I said, 'I'm having a panic attack. I need a drink of water.' And the woman at the venue was like, 'We don't have time.' And I was like, 'I don't care. 'I'm not going to make it.' What was happening? Was your heart pounding? Were you shaking? What was happening? Was your heart pounding? Were you shaking? I felt like I was choking. Despite those moments of panic, Jessica was no runaway bride. I just have to keep trying my best. It was Marvin who was an emotional wreck at the altar. PASTOR: What has been joined here today, let no... It's for me and it's for him and it's for us. I now pronounce you... But at the end of the day, it's for me. ...husband and wife. Mr and Mrs Marvin and Jessica Graaf. PEOPLE CHEER