Alan, a well-respected medical specialist, has a beautiful wife whom he loves deeply, but he never has sex with her. When she shows the slightest interest in intimacy, he picks a fight or finds some excuse to avoid her.
Sometimes if he senses she is going to be in the mood, he masturbates beforehand, leaving his wife hurt and confused when he doesn't want her.
It's hard to believe, but Alan, who is too ashamed to use his real name, is a sex addict.
Until recently, the Pennsylvania 42-year-old has led a double life, sneaking off to the computer for self-gratification. At first he looked online for erotic images and videos to get an escalating excitement he calls "the haze, the high and the full numbness."
But soon that wasn't enough, and he needed to watch a live person, or have phone sex -- up to three hours a day, sometimes "grabbing a sneak peak" from work. Eventually, Alan had an affair, texting about sex non-stop, and he could no longer hide it from his wife.
"Some people don't think that sex addiction is a real addiction, but it is," he said. "The way my heart races when I start logging on to Web sites to the build-up. I can go here and go there. What it does, it gets you high and when you are done, finished, you are calm or numb. It's almost like self-mutilation. That's the way I feel, numb and not there, like a part of my body is not there."
Alan, who is now getting help in a 12-step program, is among an estimated 5 to 6 percent of all Americans who admit to sex addiction, most of them men.
The field is new in the psychiatric world, but has gained more attention since celebrities like actor David Duchovny, Major League Baseball player Wade Boggs and British comedian Russell Brand have confessed to sex addiction.
In the year since golfer Tiger Woods checked into a Mississippi sex rehabilitation clinic, the number of those seeking treatment has jumped by 50 percent, according to Robert Weiss, founding director of the Sexual Recovery Institute in Los Angeles, which opened in 1995.
The month after Woods went into rehab, the Sexual Recovery Institute began offering information sessions that have been drawing 35 to 50 people a week.
Its Web site has had 13,000 hits in the last 30 days.
"I don't think it's accidental," said Weiss. "Even those who don't ask for help are looking for information."
There has been disagreement in the scientific community over whether people can be addicted to sex in the same way as drugs or alcohol. Two characteristics of substance abuse are building up a tolerance over time and going through withdrawal when deprived.
The American Psychiatric Association does not even include sex addiction in its Diagnostics Standards Manual IV, although it is under review for the next edition.
"The reality is that with little research and no clear diagnosis, at least for now, the treatment one receives is dependent on who you get as a therapist," said Weiss. "We have a dearth of professional, well-researched training programs and institutes."
At present there are only a handful of large out-patient clinics and only about 900 therapists who have had some training or certification, according to Weiss.
Sex addiction, like over-eating and compulsive spending and gambling, is a process addiction -- a neurobiological arousal disorder that involves the interplay of the hormones serotonin, dopamine and adrenaline.