Discrimination is being blamed for high rates of mental health problems amongst gay men and lesbians, a study suggests.
Bullying during childhood was highlighted in the study
A survey of 1,285 homosexual and bisexual men and women found just under a third had attempted suicide.
Just over 40% had had problems such as anxiety and sleep disturbance, the Imperial College researchers said.
The British Journal of Psychiatry study said there was a "likely link" with discrimination such as having been bullied at school or a recent attack.
The researchers said their study was the first to actually examine the potential effect of discrimination on the mental health of people who were homosexual or bisexual.
Eighty-three per cent of respondents said they had experienced either damage to property, personal attacks or verbal insults in the last five years, or insults and bullying at school, with many attributing these experiences to their sexuality.
The survey found that 42% of the gay men, 43% of lesbians and 49% of bisexual men and women had a clinically recognised mental health problem.
In addition to anxiety and sleep disturbance, these also included panic attacks, depressive moods or thoughts, problems with memory or concentration, compulsive behaviour or obsessive thoughts.
Around the same numbers also reported self-harming. However, no higher levels of more severe depression and psychosis were seen amongst those surveyed.
Focus on schools
Dr James Warner, a psychiatrist at Imperial College who carried out the research, said: "The results of this research show that there is a likely link between levels of discrimination and an increased risk of mental health problems.
"It seems that high levels of discrimination, including physical attacks or verbal insults and previous school bullying can lead to an increased risk of mental health problems."
He added: "Schools need to be alert to the fact that gay children are being bullied.
A spokesman for the gay rights charity Stonewall said: "These findings are not a surprise. Bullying, harassment and violence can have a detrimental effect on people's mental health."
He agreed that efforts had to be focussed on schools, adding: "The main challenge is the homophobic culture in schools, which is rampant, and something we are tackling."
Richard Brook, chief executive of mental health charity Mind, said: "Discrimination can impact negatively on a person's mental health.
"But we should be careful not see it as a simplistic causal factor in predicting mental ill health."