Long relationships have a positive effect on people's mental health - even if they are not married, a study has found.
The study has found that men and women who are in relationships for longer than five years are less likely to be depressed, to consider or attempt suicide, or to be dependent on alcohol or drugs.
The study examined 1,000 people living in New Zealand by a team at University of Otago.
It was found that longer relationships were associated with lower rates of mental health problems.
At the age of 30, 16 per cent of people who were not in a relationship showed symptoms of depression along with 23 per cent of people who had been in a relationship for less than two years.
The study also found that the rate of alcohol abuse or dependence was 12 per cent among 30-year-olds who were not in a relationship and 13.5 per cent for people who had been in a relationship for less than two years.
The researchers found that this association remained after they controlled for other factors, such as family background and previous mental health problems.
"Our study suggests that partner relationships are protective for mental health, with the protective effect increasing as the length of the relationship increases. This could be because emotional support and financial stability tends to increase over the course of a relationship," the Telegraph quoted lead researcher Sheree Gibb, as saying.
"Interestingly, we found that the legal status of the relationship did not make a difference. In other words, it was the length of the relationship that had a positive effect on people's mental health - and it did not matter if the couple was married or cohabiting.
"This is a contrast to previous studies, which have reported lower rates of mental health problems among people in legal marriages than in cohabiting relationships," said Gibb.
The findings were published in the British Journal of Psychiatry.