The happiness curve has been a relatively predictable U-shape for a long time: You are at your happiest when you’re young; then happiness declines in midlife, only to rise once again in old age. But researchers have discovered that the curve is flattening, as happiness is dipping earlier in life than it used to.

The results came out of the Global Flourishing Study, a collaboration between researchers at Harvard and Baylor University who analyzed data collected by Gallup from more than 200,000 people in 22 countries. They discovered that on average, young adults ages 18 to 29 were unhappy, while grappling with poor mental and physical health, negative perceptions of their own character, finding meaning in life, financial security, and the quality of their relationships.

Using Harvard’s Flourishing Measure—a composite of happiness and life satisfaction, physical and mental health, meaning and purpose, character and virtue, and close social relationships—researchers determined how much each participant was flourishing in their life. Now, they found, the flourishing curve is flat until around age 50, when it begins to rise again.

Researchers found this to be true across several countries, including the U.K. and Australia—but the well-being gap of younger and older adults was the widest in the U.S.

“It is a pretty stark picture,” Tyler J. VanderWeele, the lead author of the study and director of Harvard’s Human Flourishing Program, told the New York Times. “Are we sufficiently investing in the well-being of youth?”

Why is Gen Z so unhappy?

Recent research shows that life satisfaction and happiness have steadily been declining among young adults for the last decade. In the U.S., the Youth Risk Behavior Survey (YRBSS) has reported a dramatic rise in anxiety and depression among American Gen Zers, especially young women. In 2023, 53% of female high school students reported persistent feelings of sadness or hopelessness, compared with 28% of boys.

“Young people are not doing as well as they used to be,” the Global Flourishing Study authors wrote. “While causes are likely diverse, mental health concerns with young adults are clearly on the rise.”

A 2023 national survey from Harvard also found that young adults (ages 18 to 25) suffered from higher rates of anxiety and depression than younger teens. That study concluded the following factors were driving Gen Z’s declining mental health:

A lack of meaning and direction: The survey found that over half (58%) of young adults reported that they lacked “meaning or purpose” in their lives in the previous month, with half also reporting that their mental health was negatively influenced by “not knowing what to do with my life.”
Financial worries: 56% of young adults were concerned about their financial well-being.
Pressure to achieve: Half of young adults expressed that achievement pressure was negatively influencing their mental health.
Feeling that the world is falling apart: 45% of young adults reported that a general “sense that things are falling apart” caused their mental health to decline.
Loneliness and social isolation: Nearly half (44%) of young adults reported a sense of not mattering to others, while 34% reported they were lonely.
Social and political issues: Widespread issues such as climate change, gun violence in schools, and concerns about political leadership were among the topics weighing on Gen Z.

For more on happiness:

Researchers have followed over 700 people since 1938 to find the keys to happiness. Here’s what they discovered
Happier parents tap into this 1 emotion
Americans under 30 are so miserable that the U.S. just fell to a historic low ranking in the annual World Happiness Report

Gen Z’s angst is dismantling the long-established happiness curve and confounding researchers