The familiar U-shaped ‘happiness curve’—with life satisfaction bottoming out around age 50—no longer holds, according to a global study published in PLOS One. A research team led by Alex Bryson of University College London analysed almost 12 million survey responses, including 10 million from long-running US mental-health polls, 40,000 UK household interviews and nearly 2 million records from the Global Minds database covering 44 countries between 2020 and 2024. Across every country examined, self-reported distress now declines steadily with age. Unhappiness is most acute among people in their late teens and twenties, while middle-aged respondents report roughly the same levels of life satisfaction as a decade ago. The reversal is strongest in high-income English-speaking nations such as the United States and United Kingdom and weakest in parts of Africa with limited internet access. The authors say rising youth distress may reflect intensive social-media use, lingering effects of the Covid-19 pandemic and limited access to mental-health care. They caution that the shift does not mean mid-life has become easier; rather, deteriorating wellbeing among younger cohorts has flattened the curve. The findings raise concerns that today’s young adults could enter middle age carrying a longer-lasting mental-health burden unless underlying causes are addressed.