An unconquerable compulsion or just a convenient excuse?

"Sex addiction" is a subject that often prompts ribaldry rather than sympathy, especially if a Hollywood star is involved. For many people it's the butt of crude jokes, but those who feel themselves afflicted are often confused, ashamed, dispirited and horrified. Yang Wanli and Tang Yue report from Beijing.

Shi Bin's aggressive appearance - a fingernail-sized piercing in his left earlobe and a brace of tongue studs - is at odds with his gentle manner. However, the 21-year-old admitted that his "punk appearance" hinted at "a demon" inside, one he has been reluctant to acknowledge openly - an addiction to sex.

Shi said he's struggling between the frequent urges and the accompanying physical or psychological problems, but he is unable to find help. The exact number of sex addicts in China is unknown because no surveys have ever been conducted on the issue.