People Sad In Middle Age, Says Report.

Experts found that happiness and sadness follow a U-shape over a person's lifetime, with the happiest times being at the start and end of life.

During the middle years, people are more likely to feel depressed, with the peak age for depression in the UK being about 44, they discovered.

Meanwhile, pensioners can experience the same degree of happiness at 70 as youngsters aged 20.

Researchers from the University of Warwick and Dartmouth College in New Hampshire in the United States analysed data from two million people from more than 70 nations.

They found an extraordinarily consistent pattern across the countries in terms of depression and happiness levels.

Professor Andrew Oswald, from the University of Warwick, and Professor David Blanchflower, from Dartmouth College in the US, believe it stems from something inside human beings.

They said signs of mid-life depression are found in all kinds of people - and are unconnected to having young children in the house, divorce, or by changes in jobs or income.

Prof Oswald said: "Some people 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. Nobody knows why we see this consistency.

"What causes this apparently U-shaped curve, and its similar shape in different parts of the developed and even often developing world, is unknown."

Marjorie Wallace, chief executive of the mental health charity Sane, said: "This study raises intriguing questions about the processes that lead to depression in mid-life, as well as indicating what a common experience it is worldwide.

"Depression is a complex and challenging condition that remains poorly understood, with as many as one in 10 people with severe depression taking their own life."