A lot of people tend to think sex addiction doesn't actually exist. That's not just ordinary people, those of us who only ever really get to hear about the issue when ­celebrities such as ­Tiger Woods or ­Russell Brand check into an exclusive clinic and who therefore can't help ­wondering, when the news miraculously finds its way into the media, how much this is about a genuine problem, and how much about a bit of well-timed and cleverly crafted PR.

It's also something a lot of experts in the addiction field tend to think. Too much sex, they say, whether ­physical or virtual, just doesn't cut it as an ­addiction. The most radical believe the word "addiction" is merely a label to describe behaviour that does not correspond to society's norms. The purists allow "addiction" to refer only to the ingestion of certain substances, such as alcohol or drugs. Many classify excessive sex as a form of obsessive-compulsive disorder and call it "sexual compulsivity" instead. Others argue that to refer to the phenomenon as an addiction undermines an individual's responsibility for their behaviour. Still others reckon it is a myth, a byproduct of cultural and other influences.

None of which, of course, has stopped the emergence of a flourishing industry to treat the disorder (if disorder it is). Dr Patrick Carnes, the leading figure in the field and author of half a dozen books on the subject, ­including the seminal Out of the Shadows: ­Understanding Sexual Addiction, runs the Gentle Path sexual addiction programme at the Pine Grove Behavioural Centre in Hattiesburg, Mississippi, where the world's wealthiest ­sportsman, Tiger Woods, is reportedly spending six weeks (and £40,000) in a bid to save his marriage and, one ­imagines, his endorsements, after ­revelations that he may have had ­affairs with as many as a dozen women.

His specially tailored treatment programme apparently includes a vow to remain celibate for the duration of the course, as well as psychiatric ­consultation, behavioural therapy, trauma work, "relapse prevention counselling" and one-to-one sessions on shame reduction and "setting sexual boundaries". There's also art, exercise and yoga classes, as well as an apocalyptic-sounding "Disclosure Day" when Woods will have to recount to his wife Elin all of his extramarital encounters.

Carnes, who has not just won awards but had the American ­Society for the Advancement of Sexual Health's annual Carnes Award named after him, plainly believes sexual ­addiction exists. "Am I a sex addict?" his website asks, invitingly. "Assess your behaviour with our online tests." Questions range from "Is sex almost all you think about?" to "Have you engaged prostitutes and escorts to satisfy your sexual needs?", "Have you attempted to stop your online sexual behaviour?" and "Have you regularly engaged in sadomasochistic behaviour?" Carnes believes that between 3% and 6% of the US population suffer from sex addiction, often to the extent that they have ended up losing career opportunities (27%), partners (40%) and even the will to live (17%).

So are you a sex addict? The warning signs, according to Carnes, include: feeling that your behaviour is out of control; knowing there may be severe consequences if you continue; wanting and trying to stop what you're doing but feeling unable to, despite knowing the consequences; needing more and more sex to get the same high; ­spending an increasing amount of time planning, engaging in and recovering from sex; and neglecting other important areas of your life in favour of sex.

Paula Hall mostly agrees. A British sexual psychotherapist, she treats up to 70 people for sex addiction every year (almost exclusively heterosexual men; there is precious little data on women with sex addiction, nor on gay people). "The first thing to realise about sex addiction," she says, "is that it's not about having a high sex drive, nor about any particular kind of sexual activity. It's your relationship with sex that's the issue: if you use it ­consistently as a way of altering your mood, if it becomes the primary coping mechanism for the ­difficulties you're experiencing in your life. Of course, none of it may matter if you're not breaking the law, or not risking your health. Lots and lots of people turn to sex for comfort. What matters is if it's the only source of comfort you have, and if it has damaging consequences."

The people Hall sees for sex ­addiction come from all walks of life, and their addictions take many forms, from excessive use of pornography to compulsive masturbation through to fetishes, high-risk sex, paid-for sex, internet sex and multiple affairs. But there are certain common denominators. Opportunity plays a big part, she says: "Many people I treat are men who travel a lot. They have the physical and the financial opportunity to pay prostitutes, for example." Many, too, have suffered from some kind of abuse in their childhood that has "caused problems with them modulating and regulating their emotions" (Carnes's research suggests that as many as 81% of his patients in an advanced stage of recovery said they had been sexually abused as children, while 72% reported other physical abuse and 97% emotional abuse).

Increasingly, people are turning to Hall for what they see as an addiction to internet porn. "It's the crack cocaine of sex addiction," she says. "People with no predisposition towards this whatsoever can suddenly find themselves hooked onit. It's to do with the nature of the internet, the way it sucks you in, combined with the extremely high levels of stimulation it makes available. Escalation is a big issue: people find the amount of time they spend online spiralling, or end up in areas they never dreamed of going to." Some move swiftly from watching porn to seeking out real-life sexual encounters.

Tina Grigoriou, a chartered counselling psychologist who regularly deals with sex-addiction cases, concurs that such behaviour is generally "a ­manifestation of people not having the psychological resources to deal with their lives". And the best way to treat it, she believes, is with a classic anti-­addiction programme much like that originally developed by Alcoholics Anonymous. "Some people can't cope with being in a group," she says. "But for those who can, the most popular treatment seems to be the 12-step programme." Several of these groups exist, especially in America, including Sexaholics Anonymous, Sex and Love Addicts Anonymous, Sexual Compulsives Anonymous and Sex Addicts Anonymous.

Other experts are not so convinced. "There's no doubt that there are ­accepted problems around appropriate sexual behaviour," says consultant psychiatrist Dr Cosmo Hallstrom. "Some practices are acceptable, others not. Often it's a value judgment. The whole concept of sex addiction comes from the Alcoholics Anonymous world. There were addictions to alcohol, to drugs, then to exercise and to work – and they added sex. That style of treatment is certainly in vogue at the ­moment, but there are other ­approaches. Anti-testosterone drugs are of proven benefit, although not very fashionable. Standard cognitive behavioural ­therapy, the psychological approach looking at underlying ­problems, can work. So can a psychoanalytical treatment, to see how ­childhood experiences could be ­affecting adult behaviour."

Some professionals, though, are sceptical about the supposed extent of sex "addiction". Professor Mark Griffiths, a psychologist at Nottingham Trent ­University specialising in behavioural addiction, says he is sure "any behaviour can be potentially addictive" in the sense that "it becomes the most important thing in people's lives; people compromise their relationships, their jobs, their families because of it; people use it for a high, and to obtain relief". We become addicted to such behaviours, he says, "for constant reward – physiological, psychological, social and financial. Sometimes the reward is that you don't get withdrawal symptoms."

But everything, he says, is a question of context. "A healthy enthusiasm adds to a life; an addiction takes away from it. If you're a 23-year-old single guy and you're a workaholic, that's probably a pretty good thing. If you're 38 and married with two kids, it's probably not. The question is: to what degree does this behaviour impact negatively on your life? And while I'm positive that there are people out there for whom sex is the most important thing in their lives, and that genuine sex addicts with very serious problems do exist . . . I think we vastly exaggerate their number."

If sex addiction was really the problem Carnes reckons it to be, Griffiths says, "we'd have addiction centres and rehab clinics like we have ones for alcohol and drugs. There'd be one on every street corner. Whereas in Britain there are about five. Six percent of the population . . . that's a lot of people. The problem with Carnes's research is that it's all based on the people who come to see him. Which is a pretty skewed sample."

The vast majority of people who check themselves into sex addiction clinics or otherwise seek treatment for what they see as an addiction to sex are, believes Griffiths, simply ­"using the term 'addiction' to justify their behaviour. Psychologists call it functional attribution. It's about ­seeking justification through this idea that we 'really can't help ourselves'."

And in the case of high-profile ­celebrities who are allegedly addicted to sex, "they were simply in a position where they were probably bombarded with advances, and they succumbed. But how many people wouldn't do the same thing if they had the opportunity? It becomes a problem only when you're discovered, when it's in danger of harming your brand image. Look, I probably had way too much sex when I was a student. But it didn't cause any problems with the rest of my life. I don't know anything much about Tiger Woods, but if he hadn't been caught, I doubt he would see himself as a 'sex addict'."

And there wouldn't, presumably, be a clinic prepared to take £40,000 off him in exchange for a cure.

Additional reporting by Homa Khaleeli