People who care for sick or disabled family and friends are the most unhappy Australians, according to research presented at a major psychology conference.
"They have the lowest level of wellbeing in any population group," says Deakin University psychology researcher Thomas Hammond.
Close to 40 per cent report extremely severe symptoms of depression and stress, he says, citing results from the Australian Unity Wellbeing Index survey of more than 4000 carers.
They are less happy than unemployed lonely people and those who earn less than $15,000 a year.
The most stressed and depressed are those who care for a mentally ill child or a child with multiple disabilities.
The next most unhappy are those who care for a chronically ill or disabled parent.
Overall voluntary carers have a personal wellbeing score of 58.5 points out of 100, compared with the normal range of 73.6 to 76.3.
"What is really affected is their subjective wellbeing. Their level of happiness and life satisfaction," says Mr Hammond, a speaker at the Australian Psychological Society annual conference in Cairns.
The people in the survey are informal unpaid primary carers, who are usually looking after a family member or close friend.
"Being a carer can be quite burdensome. But some studies show some people thrive in the role," says Mr Hammond, who believes there is an urgent need for better support systems.
"Despite the considerable benefits of informal caring there is a substantial cost.
"More often than not it is the carers who pay the price.
"When carers suffer stress and depression we have another person with a different type of disability."