Does your age have anything to do with your happiness? In a study, researchers found people's happiness changes with age. After childhood, the happiness level goes up again only after the age of 70.

Although happiness may vary between people based on personal experiences, the researchers found that life satisfaction – one of the factors that determines happiness – decreases after the age of nine and increases between the ages of 70 and 96.

The study, published in the journal Psychological Bulletin, examined 443 samples from different longitudinal studies with a total of 460,902 participants. The participants were asked to describe how they felt about themselves during childhood, young adulthood and old age.

"The findings show that the respondents' life satisfaction decreased between the ages of 9 and 16, then increased slightly until the age of 70, and then decreased once again until the age of 96," researchers said in a news release.

They believe the changes to the body and social life during puberty can be the reason for the reduced life satisfaction during the period.

Apart from life satisfaction, researchers used positive emotional states and negative emotional states to measure happiness.

Positive emotional states declined from age nine to 94, while negative emotional states varied between the ages of 9 and 22, went down until age 60 and then increased after that. Researchers say the decreased well-being of the participants in late adulthood might be because of deteriorating health.

"This could be related to the fact that in very old people, physical performance decreases, health often deteriorates, and social contacts diminish; not least because their peers pass away," said Susanne Bücker, a study author. "Overall, the study indicated a positive trend over a wide period of life, if we look at life satisfaction and negative emotional states."

Researchers hope the findings "could provide significant guidance for the development of intervention programs, especially those aimed at maintaining or improving subjective well-being late in life."