"The U-Shaped Happiness Curve and Midlife Crisis Are Outdated... The Peak of Unhappiness in Life Is Now in Young Adulthood"

"Mental Health Crisis Peaks in Early Adulthood"
Unhappiness Highest Among 18?24-Year-Olds, Not Middle Age

Contrary to the common belief that happiness follows a U-shaped curve throughout life, with the lowest point in middle age, a new study has found that the period of highest unhappiness-the "Unhappiness Hump"-actually occurs between the ages of 18 and 24.

A research team led by Professor David Blanchflower from the Department of Economics at Dartmouth College in the United States examined whether the "Unhappiness Hump" curve has shifted in line with changes in the mental health of younger generations. The team analyzed survey data from the U.S. Centers for Disease Control and Prevention (CDC), which covered 10 million adults between 1993 and 2024, as well as longitudinal household study data from the United Kingdom, which tracked 40,000 households from 2009 to 2023.

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"Mental Health Most Fragile Among 18-24 Year Olds"

The results showed that while happiness used to follow a U-shaped curve, with unhappiness peaking in middle age, this pattern has recently disappeared. Instead, the mental health of younger generations is now the most fragile. In other words, the mental distress experienced by young people has significantly worsened compared to previous generations. Unhappiness now peaks between the ages of 18 and 24 and tends to decrease as people get older. The research also found that mental distress, such as anxiety and feelings of despair, has increased much more sharply among young women than in previous generations.

Unhappiness Lower in Middle Age Than in Youth

The team further analyzed mental health data from 2 million people across 44 countries, including the United States and the United Kingdom. Data from 2020 to 2025 also showed that the "Unhappiness Hump," which previously peaked in middle age, has disappeared, and the trend of decreasing unhappiness with age remains consistent. The researchers explained, "Factors such as unstable job prospects for young people due to economic downturns, insufficient mental health care, the impact of the COVID-19 pandemic, and increased use of social networking services (SNS) may have contributed. However, further research is needed to clarify the exact causes."

Regarding these findings, the research team emphasized, "The risk of developing mental disorders is highest among young people and gradually decreases with age. As the deterioration of mental health among the youth becomes more pronounced, a different approach from the past is required."

This study was published on August 27 in the international journal PLOS One.