Jessie* is 30 years old, with a full-time job and what she describes as a "happy marriage" — but in secret, she regularly fires off messages cruising for casual sex, masturbates three times a day and constantly fantasises about steamy, meaningless encounters.
The university graduate believes she has been a sex addict since the age of 14, and has even passed on sexually transmitted infections to her husband because of her reckless behaviour.
"I engage in high-risk and detrimental sexual behaviours that I have trouble controlling," she said, adding that her urges were "intermittent" but had a "serious impact" on her wellbeing and relationships with family, friends and her current and former partners.
"I often feel deep shame as a result, yet I cannot control these actions," she admitted.
The young woman, who has been diagnosed with anxiety and takes antidepressants, said she has "honestly no idea" what to do about it.
Scientists are still divided over whether sex addiction is really a clinical disorder — and if it is, how it can be accurately identified and treated.
With unfaithful celebrities and even some accused of harassment and assault blaming sex addiction, there is widespread doubt about the condition's veracity. After the revelations about Harvey Weinstein and Kevin Spacey, both checked themselves into rehab, leading three non-profit organisations to come out against the idea that sex or pornography can be addictive.
The field is hard to study because of difficulties in monitoring the brain's arousal over a typical day. But Michael Walton, researcher at the University of New England in NSW, said "a small group could be addicted".
Mr Walton and psychologists at UNE and the Centre for Addiction and Mental Health in Toronto estimate around 3-6 per cent of the population could have a true "hypersexual" disorder. For others, there may be more complex factors at play.
When Jordan* was 15, he was having 50 orgasms a day. That may sound like a teenage boy's dream, but was for this young man a distressing compulsion that left him feeling depressed and guilty, and failing at school.
The 19-year-old student, who takes medication for severe clinical depression, believes he has been a sex addict since the age of 13, with his problem peaking two years later, when he was spending 14 hours each week masturbating and watching porn. "Porn is like cocaine," he said. "I feel addicted and I can't stop."
Mr Walton said there are undoubtedly people who struggle to control their sexual behaviour, causing them to experience considerable emotional distress, but their level of sexual activity may vary.
"One of my case studies was married but involved in swinging with their husband," said Mr Walton, who has surveyed more than 1500 people over several years. "They would sleep with multiple people, up to 20 in a weekend, and that person is mostly OK, there may just occasionally be some unease or fatigue. Then you've got someone else who's watching quite a lot of porn and masturbating. You've got someone whose output is way above someone who's feeling distressed."
The addiction is not necessarily about the specific amount of sex or masturbation people are engaging in — it's about whether their behaviour is causing them anxiety. Those at the higher end can also become socially isolated, neglect healthy behaviour such as exercise and experience immediate physical issues such as infection or penile trauma.
"A lot of people have a psychological problem of which hypersexuality may be a symptom," said Mr Walton. "With hypersexual disorder, the numbers are probably a lot lower.
"It could be a symptom of a host of things. For a lot of people, it could be about sexual satisfaction, their relationship, monogamy.
"There's a cluster of people with clinical depression and anxiety — is the low mood driving it?"
Hypersexuality has been identified as a symptom of borderline personality disorder, bipolar, neurological conditions such a Parkinson's, abuse of drugs or alcohol and, in a limited number of cases, the side-effect of prescribed medication.
But Mr Walton and his colleagues "wouldn't rule out classifying it in the future".
Aaron* is a 42-year-old married man who visits escorts two or three times a week and cruises for sex with men or women at parks or public toilets once or twice a month.
The father-of-one said he is "habituated to casual or anonymous sex" and would "choose prostitutes randomly and have casual sex with men, even though I have no romantic or physical attraction" towards them.
He said he frequently "pursued sex without real thought", and while he knew cheating was wrong and regretted it afterwards, an attempt to stop for three months was followed by "intense binges that involved more than 30 partners in a month".
Aaron said his anonymous encounters had only increased his "sexual energy" with his wife, and the negative consequences of his hypersexuality were "largely financial", since he had spent "thousands of dollars a year on paid sex".
Aaron said that he felt "almost no emotion" about his sexual activities although he knew that his sexual behaviour was "far outside the boundaries and expectations of his marriage". He said he thrived on the "freedom" of transgressive sex where there were "no expectations" on his behaviour.
He did not report any mental health issues, but his score on a validated test found he had "extremely severe" levels of depression and anxiety.
Around 80 per cent of self-identified sex addicts are male and many suffer from low self-esteem or report being sexually abused as children. Other recurring factors were that individuals were Christian and their behaviour was incongruent with their beliefs, or there was some confusion around their sexual orientation. Researchers raised questions around sex education.
Mr Walton said: "We've got to agree on a diagnostic that's non-pejorative and non-judgemental."
His research with associate professors Amy Lykins and Najot Bhullar from UNE and Dr James Cantor from the Toronto addiction centre concludes that "it is time" hypersexuality was at least recognised as "a psychosexual behavioural problem".
Previous research has found that hypersexual individuals (particularly men) have a higher propensity for sexual excitement or arousal compared to the general population. "A lot of people had no recognition of what their emotions or feelings were when aroused," said Mr Walton.
While much of the research so far relies on perceptions, and the matter is complicated by celebrities going to "very expensive clinics", Mr Walton said what we know is that some people display problematic sexual behaviour.
"Where it really becomes a problem is around sexual risk taking, especially if it's combined with drugs. You get unsafe sex, HIV, that combination of risky sexual behaviour with high excitation."
He said people often self-manage psychological issues including relationship problems and that although high states of sexual arousal may adversely impact cognitive processing, the researchers do not consider that typically an individual's sexual behaviour is substantively beyond one's self-control.
That's important in a legal sense. Mr Walton said: "One of the problems with sex addiction model is, how is the court going to interpret that?
"What is the level of control? These disorders have potentially very serious implications in court."
WHERE TO GET HELP:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youth services: (06) 3555 906
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• The Word
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• CASPER Suicide Prevention
If it is an emergency and you feel like you or someone else is at risk, call 111.
* Names have been changed.
Experts stress staying active to manage arthritis and slow its progression.