A groundbreaking new study published in the open-access journal PLOS One by David Blanchflower and colleagues from Dartmouth College challenges a long-held belief about a universal pattern in mental wellbeing known as the “unhappiness hump.” Traditionally, this phenomenon describes a midlife peak in psychological distress—characterized by elevated levels of worry, anxiety, and depression—that declines in older age. However, recent evidence suggests this pattern is vanishing, potentially triggered by deteriorating mental health among younger generations. This revelation might alter how societies understand and approach mental health across life stages globally.
For decades, psychological research has consistently identified a U-shaped curve in subjective wellbeing spanning the human lifespan. From childhood, emotional wellbeing tends to dip gradually, hitting its lowest point in midlife—typically around the late 40s or early 50s—before rebounding into older adulthood. This pattern correlates with what has been called the “unhappiness hump,” a temporal elevation in mental ill-being during middle age. It has been widely documented across numerous countries, both developed and developing, suggesting a universal developmental trajectory of psychological distress linked to age.
Blanchflower and his team undertook an extensive analysis of survey data drawn from two major national sources, the U.S. Centers for Disease Control and Prevention (CDC) and the U.K.’s Household Longitudinal Study. The CDC data encompassed responses from over 10 million American adults collected between 1993 and 2024, while the U.K. dataset included information from about 40,000 households, spanning 2009 to 2023. Both datasets contained detailed self-reported measures of mental health, enabling the authors to evaluate longitudinal trends in ill-being across different age groups over more than two decades.
Their analysis revealed a striking pattern: the classic midlife hump in mental ill-being has nearly vanished in recent years within both the U.S. and U.K. populations. Contrary to previous decades, psychological distress no longer peaks in middle age. Instead, ill-being appears to steadily decline with age, meaning younger individuals now experience the highest levels of mental health challenges. Notably, mental health levels among middle-aged and older adults remained relatively stable, indicating that the disappearance of the hump is driven primarily by a marked reduction in wellbeing among younger cohorts, rather than improvements in later life stages.
To test whether this trend was unique to these two countries or indicative of a broader global phenomenon, the researchers expanded their inquiry by examining the Global Minds dataset. This international study, consisting of mental health survey data from nearly 2 million individuals across 44 countries—collected between 2020 and 2025—corroborated their findings. The analysis demonstrated that the traditional unhappiness hump has disappeared worldwide, with mental ill-being peaking among younger adults and declining through the life course across diverse cultural and socioeconomic contexts.
The underlying causes for this radical shift remain complex and speculative. Blanchflower and his team propose several potential contributing factors. Foremost among these is the long-lasting economic fallout from the 2007–2009 Great Recession, which severely impaired job prospects and financial stability for young adults entering the labor force. Additionally, persistent underinvestment in mental health services may have left a generation vulnerable to untreated psychological disorders. The unprecedented social disruptions from the COVID-19 pandemic likely exacerbated existing stressors by increasing isolation and uncertainty for young people during critical developmental periods.
Furthermore, increased exposure to social media and digital technologies could be shaping mental health trajectories in unforeseen ways. While online platforms foster connectivity, they also expose users to cyberbullying, social comparison, misinformation, and disrupted sleep patterns—all of which are linked to anxiety and depression. These multifaceted sociocultural and economic pressures may collectively explain why younger individuals’ mental health has declined so starkly, disrupting the once ubiquitous midlife peak in unhappiness.
This finding has profound implications for public health policy and mental health interventions. Historically, resources and preventative efforts have often prioritized middle-aged adults, based on assumptions about when psychological distress is most likely to arise. The revelation that mental ill-being is now highest among the young demands a paradigmatic shift in focus toward early identification, support services, and policy measures that address the unique challenges facing young people today. Enhanced investment in accessible mental health resources tailored for youth could mitigate this emerging crisis.
Moreover, the disappearance of the unhappiness hump may necessitate reexamining psychological theories of human development and wellbeing. The U-shaped curve has been linked to life-course events such as career pressures, family responsibilities, and health decline, traditionally most acute in middle age. The present data suggest that contemporary youth face unprecedented stressors that alter these dynamics, warranting updated models that incorporate socio-historical context, economic uncertainty, and digital culture influences on mental health trajectories.
Critically, Blanchflower and colleagues emphasize that the reasons behind these changes are still debated and require further empirical investigation. Untangling the relative contributions of economic, social, cultural, and biological factors will be essential for designing effective interventions. Longitudinal studies incorporating genetic, environmental, and behavioral data may shed light on causal mechanisms and identify protective factors that can be leveraged to bolster youth resilience and wellbeing.
The authors conclude with a stark warning, underscoring the urgency of addressing this emerging mental health crisis among young people. The traditional peak of ill-being in midlife appears to have shifted leftwards, meaning that psychological distress manifests earlier and more intensely than in previous generations. Without concerted effort from governments, healthcare providers, educators, and communities, this trend threatens to entrench lifelong mental health challenges with far-reaching societal consequences.
As the global community grapples with the mental health ramifications of economic instability, digital transformation, and pandemic recovery, this study offers timely insights. By refocusing attention to the vulnerable young population and acknowledging the dissolution of the historical unhappiness hump, policymakers and mental health advocates can develop targeted strategies to halt and reverse the decline in youth mental health. The findings underscore the critical need for multisectoral cooperation and innovative approaches to promote psychological resilience in an increasingly complex and challenging world.
The comprehensive analysis by Blanchflower et al. not only advances scientific understanding of lifespan mental health trajectories but also serves as a clarion call for action. Their pioneering work opens new avenues for research into the socio-psychological determinants of mental health, highlighting an urgent public health priority. As investigations continue, this study lays the foundation to rethink how societies support the wellbeing of their youngest generations and safeguard a healthier future for all.
Subject of Research: Not applicable
Article Title: The declining mental health of the young and the global disappearance of the unhappiness hump shape in age
News Publication Date: 27-Aug-2025
Web References: http://dx.doi.org/10.1371/journal.pone.0327858
References: Blanchflower DG, Bryson A, Xu X (2025) The declining mental health of the young and the global disappearance of the unhappiness hump shape in age. PLoS One 20(8): e0327858.
Image Credits: Blanchflower et al., 2025, PLOS One, CC-BY 4.0
Keywords: mental health, unhappiness hump, wellbeing, youth, lifespan psychology, survey research, global mental health trends, COVID-19 pandemic, social media impact, economic recession, psychological distress, public health
