By Helen Neill
BBC Radio 1 & 1xtra Health Reporter
Sex and relationship therapists are seeing an increase in the number of men suffering from sex addiction, a BBC investigation suggests.
The Internet means pornography has become more easily available
Almost 80% of the 43 therapists in the survey said sex addiction is a problem.
Many said the obsessive use of internet pornography is now the most common form of the condition.
The counselling service Relate has also seen a "huge increase" in people who say compulsive sexual behaviour is straining their relationship.
The therapists said that in the most extreme cases people can lose their jobs or partners because of their obsession, with some spending up to eight hours a day looking at pornographic websites.
In the questionnaire, conducted for BBC Radio 1's Newsbeat, 74% said it was becoming increasingly common to see excessive use of internet pornography as a problem in relationships.
Whereas frequent casual sex, risk-taking sex and use of prostitutes was seen as fairly common amongst sex addicts, the use of internet pornography was seen as very common - internet pornography and 'cybersex' were often seen as anonymous, cheap and safe.
One respondent described the worst case they had come across. "The most debilitating was a man who had to have sex 10-12 times every day. Lately with internet pornography men seem to get addicted quicker".
Christine Lacy, Relate Sex therapy consultant said those with sex addiction problems felt their lives were: "spiralling out of control".
She said: "In the last two years alone, Relate has witnessed a huge increase in people presenting excessive use of internet pornography, and compulsive sexual behaviour as issues affecting their relationships.
"Their partners feel betrayed and very angry and whilst many partners are supportive, in some cases they cannot continue the relationship which obviously has a severe impact on any children they may have, their jobs and their wider families."
"Relate counsellors working with teenagers have reported that the instant availability of pornographic images on the internet and mobile phones has worrying implications for their ability to have normal sexual relationships as they grow up."
The questionnaire was completed by 43 sex and relationship therapists from across the UK.