Legalising same-sex marriage may create a healthier environment for gay men, say US researchers.The number of visits by gay men to health clinics dropped significantly after same-sex unions were allowed in the state Massachusetts.This was regardless of whether the men were in a stable relationship, reported the American Journal of Public Health.A UK HIV charity said there was a clear link between happiness and health.Research has already suggested that gay men are more likely to suffer from depression and suicidal thoughts than heterosexual men, and that social exclusion may be partly responsible. 'Lasting repercussions'Same-sex marriages are legal in six US states, with Massachusetts the first to allow them in 2003.Researchers from Columbia University Mailman School of Public Health surveyed the demand for medical and mental health care from 1,211 gay men registered with a particular health clinic in the 12 months prior to the change, and the 12 months afterwards.