New research has found that adults over age 30 are not as happy as they used to be, but teenagers and young adults are happier than ever.
"Our current culture of pervasive technology, attention-seeking, and fleeting relationships is exciting and stimulating for teens and young adults, but may not provide the stability and sense of community that mature adults require," said Jean Twenge, professor at San Diego State University in the US.
The researchers analysed data from four nationally representative samples of 1.3 million Americans aged 13 to 96 taken from 1972 to 2014.
Twenty-eight percent of adults ages 18 to 29 said they were "very happy" in the early 1970s, versus 30 percent in the 2010s.
Over the same time, teens' happiness increased: 19 percent of 12th graders said they were "very happy" in the late 1970s, versus 23 percent in the 2010s.
The findings suggest that after 2010, the age advantage for happiness found in prior research vanished.
There is no longer a positive correlation between age and happiness among adults, and adults older than 30 are no longer significantly happier than those ages 18 to 29.
The researchers also found that drop in happiness occurred for both men and women.
The study was published in the journal Social Psychological and Personality Science.