Once a universal midlife slump, unhappiness now peaks in the youngest generations, raising urgent questions about how social, economic, and digital forces are reshaping mental health worldwide.
Study: The declining mental health of the young and the global disappearance of the unhappiness hump shape in age. Image credit: UlrikaArt/Shutterstock.com
The “unhappiness hump” is a well-documented global trend of increasing unhappiness with aging that peaks in middle age and declines thereafter. However, a new study published in PLOS ONE suggests that it has largely disappeared worldwide, with worsening mental health among young people emerging as the leading explanation.
Background
A U-shaped well-being trend and a hump-shaped ill-being or unhappiness trend continued to be human psychology's most widely documented features since their discovery in 2008. The U-shaped trend indicates that well-being, including life satisfaction and happiness, declines until middle age, then rebounds later in life. On the other hand, the hump-shaped unhappiness trend describes that ill-being, including worry, stress, and depression, increases with age until middle age, and then declines later in life.
However, recent evidence suggests a global decline in well-being among young people, which may potentially affect universal trends in human psychology. However, it remains uncertain how these recent changes in well-being in youth impact U-shaped well-being and hump-shaped unhappiness trends with age.
In the current study, David Blanchflower of Dartmouth College, U.S., and colleagues addressed this question by analyzing mental health survey data collected from the United States and the United Kingdom.
The Centers for Disease Control and Prevention conducted surveys on more than 10 million adults in the United States between 1993 and 2024. In the United Kingdom, the ongoing U.K. Household Longitudinal Study collected mental health data from 40,000 households between 2009 and 2023.
Key findings
The study analysis revealed that the hump-shaped unhappiness in age, which used to be a universal trend in human psychology, has disappeared in recent years in the U.S. and U.K. This trend has been replaced by a new trend, which shows that subjective unhappiness is highest among younger people and declines over the life course, probably due to a deterioration in mental health among younger people.
The subjective unhappiness among older adults remained relatively stable, while middle-aged groups showed only modest changes rather than sharp increases or decreases.
The researchers further confirmed this new trend by analyzing the mental health data of nearly 2 million people from 44 countries, which was collected between 2020 and 2025 by a mental health study called Global Minds.
Why did the trend change?
The researchers believe that this global change in unhappiness trend is not solely driven by the coronavirus disease 2019 (COVID-19) pandemic, as they observed that the decline started before the pandemic in both the U.S. and the U.K.
They emphasize that multiple factors may potentially influence the trend of declining well-being among younger people. One potential factor is the long-term impacts of the Great Recession of 2008 on job prospects. The paper notes some “scarring effects” on younger cohorts’ labor market prospects but finds little evidence that the financial crisis alone explains the decline.
The authors also discuss how the underfunding of mental health services in the U.S. and U.K. may have affected youth wellbeing since the Recession. Delayed access to treatment may have prolonged the duration of suffering with poor mental health conditions, potentially contributing to the declining well-being among younger people.
Several studies have linked the COVID-19 pandemic to the deterioration of mental health among young people. The UK data analyzed in the current study also reveals that the pandemic has triggered hopelessness more among younger people compared to older people.
The advent of smartphone technologies and the subsequent rise in social media use have significantly impacted young people’s perceptions of themselves and their lives relative to their peers’ portrayal of them via social media. This change in perception may result in greater dissatisfaction in many aspects of life, including income, lifestyle, and body image-related dissatisfaction.
The rise in social media use coincides with the declining well-being among young people. A significant improvement in self-reported well-being has been observed among people with limited smartphone and internet access. The paper notes a growing pool of natural experiment evidence suggesting a likely causal link between social media use and deterioration in mental health among young people, though debate remains. Some researchers have called for restricting young people’s smartphone access and regulating social media content. Still, the authors present this as part of an ongoing discussion rather than a settled policy prescription.
The paper also raises the possibility that shifting expectations among younger cohorts, such as challenges in housing affordability and tougher labor market conditions, may contribute to the worsening patterns.
Overall, the study findings indicate that young people in the U.S, U.K., and across 44 countries experience the highest level of mental ill-being in recent years, which is a substantial change from the past when mental ill-being peaked in middle age. These findings are concerning and highlight the need for addressing the factors associated with mental health crisis among young people.
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