Middle age is miserable for many, according to a study using data from 80 countries showing that depression is most common among men and women in their 40s.
The British and U.S. researchers found that happiness for people in 72 countries 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.
On average, they found, well-being bottoms out at about age 48 1/2 around the world. But those lows varied quite a bit, ranging from about age 36 in the United Kingdom to about age 66 in Portugal.
The average low point in the U.S. was 44 1/2, although researchers noted a suprising blip in their results: happiness among American men continued to fall until about age 53.
In the U.S., researchers used data that rated well-being by asking this question: "Taken all together, how would you say things are these days — would you say that you are very happy, pretty happy or not too happy?"
In Europe, they asked: "On the whole, are you very satisfied, fairly satisfied, not very satisfied or not at all satisfied with the life you lead?"
“For the average persons in the modern world, the dip in mental health and happiness comes on slowly, not suddenly in a single year,” Oswald said. “Only in their 50s do people emerge from this low period.”
About eight nations — mostly in the developing world — did not follow the U-shaped pattern for happiness levels, Oswald and his colleague David Blanchflower of Dartmouth College in the United States wrote.
“It happens to men and women, to single and married people, to rich and poor, and to those with and without children,” Oswald said. “Nobody knows why we see this consistency.
One possibility may be that people realize they won’t achieve many of their aspirations at middle age, the researchers said.
Another reason could be that after seeing their fellow middle-aged peers begin to die, people begin to value their own remaining years and embrace life once more, researchers speculated.
The study's findings generally reflect previous research that shows people gain a sense of satisfaction as they age, said Laura L. Carstensen, director of the Center on Longevity at Stanford University.
"Shrinking time horizons tend to change people's goals," she said. "We predict that people will experience more emotional satisfaction as they age."
She cautioned that the study offers a gross analysis of a fairly simple measure of happiness, not necessarily clinical depression.
The consistent dip in well-being is likely sparked by the challenges of middle age, said Dr. Robert N. Butler, president of the International Longevity Center — USA, in Manhattan. It's the time when people pause to evaluate the crucial questions of their lives.
"Have you really succeeded? Is this really the right marriage? How are the children?" he said.
After about age 60, those questions may be resolved.
"The stormy part is over and you sort of come to terms," he said.
The good news, according to the new study, is that if people make it to age 70 and are still physically fit, they are on average as happy and mentally healthy as a 20-year old.
MSNBC.com health writer JoNel Aleccia and Reuters contributed to this report.