Research show people are most likely to suffer from depression when they hit 44 If you've just turned 40 and think you're heading for a mid-life crisis, you may wish to look away now.

For scientists have confirmed that we really are most likely to feel depressed when we reach middle age.

They suggest happiness and depression follow a U-shape over the course of a lifetime.

So while most of us enjoy a happy start and end to life, there is a trough in the middle, with 44 the year when depression peaks.

And the low period does not lift significantly for several years.

Researchers from Warwick University in Britain and Dartmouth College in the U.S. who analysed data on two million people from 70 nations found an extraordinarily consistent pattern in terms of depression and happiness levels.

From Australia and Italy to Nicaragua and Azerbaijan, they witnessed the same U-shape.

While during the middle years we are more likely to feel depressed, pensioners can experience the same degree of happiness at 70 as those aged 20.

Many previous studies have suggested psychological well-being stays relatively flat and consistent as we age, but the latest report suggests this is not the case.

Using a sample of a million Britons, researchers found both men and women faced their biggest dip in happiness at 44, regardless of marital status, wealth or children.
 

In the U.S., by contrast, there was a big difference between the sexes, with unhappiness peaking at about 40 for women and 50 for men.

Warwick's Professor Andrew Oswald said signs of mid-life depression are found in all kinds of people.

"Some suffer more than others but in our data the average effect is large. It happens to men and women, to single and married people, to rich and poor, and to those with and without children."

He said that what caused the U-shaped curve was unknown, but added: "It looks from the data like something happens deep inside humans.

"For the average person in the modern world, the dip in mental health and happiness comes on slowly, not suddenly in a single year.

"Only in their fifties do most people emerge from the low period. But encouragingly, by the time you are 70, if you are still physically fit, then on average you are as happy and mentally healthy as a 20-year-old.

"Perhaps realising that such feelings are completely normal in midlife might even help individuals survive this phase better."

The study - Is Well-Being U-Shaped Over The Life Cycle? - will be published in the forthcoming Social Science & Medicine journal.

Marjorie Wallace, chief executive of the mental health charity Sane, said: "Depression is a complex and challenging condition that remains poorly understood.

"We welcome any scientific contribution to our understanding of this illness."