Lesbians, gays and bisexuals who are out have lower stress hormones than those who hide their sexuality.
Researchers at the Centre for Studies on Human Stress (CSHS) at the Louis H Lafontaine Hospital in Montreal found that LGBs who had come out as gay had fewer symptoms of anxiety, depression and burnout.
Lead author Robert-Paul Juster said: "Our goals were to determine if the mental and physical health of lesbians, gay men and bisexuals differs from heterosexuals and, if so, whether being out of the closet makes a difference.
"We used measures of psychiatric symptoms, cortisol levels throughout the day, and a battery of over twenty biological markers to assess allostatic load."
Allostatic load refers to the stress hormone cortisol. Cortisol contributes to wear and tear exerted on our bodies and combined with stress is a person's allostatic load.
Juster said: "Contrary to our expectations, gay and bisexual men had lower depressive symptoms and allostatic load levels than heterosexual men.
"Lesbians, gay men, and bisexuals who were out to family and friends had lower levels of psychiatric symptoms and lower morning cortisol levels than those who were still in the closet."
Matter of public health
The study suggests that LGBs who are out may have developed coping strategies because of the stigma-related stress they faced, meaning they are better able to manage stressors.
It looked at 87 men and women who were aged around 25. They filled out psychological questionnaires and provided saliva samples to measure stress levels.
Sonia Lupien, director of the CSHS, said testing stress levels can help to detect people at risk of health problems: "Chronic stress and misbalanced cortisol levels can exert a kind of domino effect on connected biological systems.
"By looking at biomarkers like insulin, sugar, cholesterol, blood pressure, adrenalin, and inflammation together, an allostatic load index can be constructed and then used to detect health problems before they occur."
The research Juster, said, has implications for political debates: "Coming out might only be beneficial for health when there are tolerant social policies that facilitate the disclosure process.
"Societal intolerance during the disclosure process impairs one's self-acceptance that generates increased distress and contributes to mental and physical health problems.
"As the participants of this study enjoy progressive Canadian rights, they may be inherently healthier and hardier.
"Coming out is no longer a matter of popular debate but a matter of public health. Internationally, societies must endeavour to facilitate this self-acceptance by promoting tolerance, progressing policy, and dispelling stigma for all minorities."