(USA TODAY) -- After age 50, daily stress and worry take a dive and happiness increases, according to an analysis of more than 340,000 adults questioned about the emotions they experienced "yesterday."

The research, published online Monday in the journal Proceedings of the National Academy of Sciences, shows that young adults experience negative emotions more frequently than those who are older. Negative emotions, such as stress and anger, are similar in that they consistently decline with age, but worry holds steady until around 50, when it drops sharply, the study shows.

The analysis is based on a Gallup phone survey of 340,847 adults, ages 18-85, which was compiled in 2008 as the first year of a 25-year effort to measure well-being in the USA.

The Gallup Organization and the Tennessee-based Healthways Corp. created the Gallup-Healthways Well-Being Index, in which about 1,000 adults each day were surveyed from Jan. 2 to Dec. 31 to get a real-time view of well-being. Respondents were asked about emotions such as enjoyment, happiness, stress, worry, anger and sadness and were asked to describe how they felt "yesterday."

"After 50 is when things start dropping off dramatically in terms of worry and stress. That's the turning point in some ways, but it's not a magic number," says study co-author Arthur Stone, a professor of psychiatry and psychology at Stony Brook University in New York. He is also a senior scientist with Gallup.

Stress is "constantly dropping, but the curve gets much steeper after age 50," he says. At age 50, 42% cite "a lot" of stress, compared with 35% at 58, 29% at 62 and 20% by 70.

The study also found that women reported greater stress, worry and sadness than men at all ages.

The research also confirms earlier studies on overall life satisfaction, which show that perceptions of well-being become more positive after 50. But the new study gives additional insight into daily emotions, which psychologist Laura Carstensen of Stanford University says is significant.

Carstensen, founding director of the Stanford Center on Longevity, has done similar research in which 184 people ages 18-94 were given pagers and asked to share their emotions when beeped during the day. That type of research is costly and can't be done with large numbers, she says.

The Gallup study is important because it "appears to be capturing the same phenomenon with a very short measure," Carstensen says.

The effect of the recession on emotions in 2008 is unclear. Stone's guess is that stress and worry were probably higher than usual that year, but the study doesn't attempt any comparisons, he says.

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