China daily----Middle age is truly miserable, according to a study using data from 80 countries showing that depression is most common among men and women in their forties.

The British and US researchers found that happiness for people ranging from Albania to Zimbabwe follows a U-shaped curve where life begins cheerful before turning tough during middle age and then returning to the joys of youth in the golden years.

Previous studies have shown that psychological well-being remained flat throughout life but the new findings to be published in the journal Social Science & Medicine suggest we are in for a topsy-turvy emotional ride.

"In a remarkably regular way throughout the world people slide down a U-shaped level of happiness and mental health throughout their lives," Andrew Oswald at Britain's Warwick University, who co-led the study, said on Tuesday.

The researchers analyzed data on depression, anxiety levels and general mental health and well-being taken from some 2 million people in 80 countries.