Results of the Australian Psychological Society's Stress and Wellbeing in Australia in 2011 survey have shown that young adults aged 18 to 25 are the most stressed in the nation.

The survey also found one in three Australians did not seek help to deal with stress and 40 per cent turned to food and alcohol as their most common de-stressing technique, even though half of them knew it did not work.

The society's executive director, Lyn Littlefield, said the national survey of 1500 people pointed out several surprising findings.

''I don't think many people would be surprised to find people under 25 are stressed, because we know this is a period of adjustment in their life, when they're leaving school and trying to get a job,'' she said.

''But it is surprising that their stress levels are higher than older adults and that we tend to stress less the older we get.

''I think it is because by the time you reach those older ages, you tend to have dealt with quite a lot in your life and found different ways to cope with things.''

Professor Littlefield said the main cause of young people's stress tended to be their jobs, including being disinterested, not feeling valued and being underpaid.

''In contrast, older people tend to have worked out a life that suits them to a degree and also tend to have put good supports in place,'' she said.

While Australia's stress levels were similar to other westernised countries, such as the United States and Britain, the survey found one in eight people (12 per cent) reported severe stress, one in three had experienced depressive symptoms and one in four experienced anxiety.

Men tended to be more stressed about finances and the political climate while women stressed about family issues, personal health and the wellbeing of others.

People who were divorced or experiencing breakdown reported significantly higher levels of stress, but only in the 12 months after their relationships fell apart.

Professor Helen Christensen, from the Australian National University's School of Mental Health Research, said the most concerning statistic was that 30 per cent of people did not seek help.

Of those who did seek help, only 15 per cent turned to mental health professionals, while 25 per cent relied on family and friends. Professor Christensen said this could be problematic.

The study found the most effective strategies for managing stress were spending time with friends (60 per cent), listening to music (55 per cent) and watching TV (55per cent).