New research released this week challenges the long-held belief that our happiness levels hit a low point in middle age, causing us to embark on a spending spree of sports cars as part of the 'mid-life crisis.'

According to the results of a 25-year study by the University of Alberta, Canada, an increase in our level of happiness starts in our teens and early twenties, but doesn't necessarily fall as we grow older and reach mid-life.

To research more about happiness levels as we age, and to observe the ups and downs of happiness at different ages and life stages in the same individual, the team of researchers followed two groups of participants for up to 25 years. A group of high school seniors were followed from age 18 through to 43, and a group of university seniors were followed from age 23 to 37.

At different stages during the study the participants were asked questions such as 'How happy are you with your life right now?' The researchers did not ask for examples of happiness; participants simply answered using a rating scaled from 'not very happy' to "very happy." The researchers also did not give any definitions of happiness to the participants.

The results showed that after leaving high school and university, happiness levels increased right through to the 30s in both samples, showing that happiness is not only for the young. And only a slight decrease in happiness was seen by age 43 and only in the 'high school' sample, going against the myth of the mid-life crisis.

However there are other factors that can influence happiness levels such as marital status, unemployment, and physical health, and levels of happiness can differ in different individuals based on these factors.

"If I'm divorced and unemployed, and I have poor health at age 43, I'm not going to be happier than I was at age 18," commented Nancy Galambos, one of the study's authors, "It's important to recognize the diversity of experiences as people move across life."

The team believe that the results are important as happiness is key to our well-being, with happier people known to be healthier and live longer. The Canadian government is even collecting information about happiness as part of Statistics Canada's General Social Survey questionnaire.

"It's seems trite -- 'just be happy' -- but behind that are the policies shaping society," says Harvey Krahn, another of the study's co-authors, "The policy implications of the study are about changing the conditions that cause grief, like being unemployed, like losing your home, inequality, being a refugee, crime, addictions -- these things will make you less happy, age notwithstanding."

The study was published in the journal Developmental Psychology.