A new survey-based study suggests that the "unhappiness hump" -- a widely documented rise in worry, stress, and depression with age that peaks in midlife and then declines -- may have disappeared, perhaps due to declining mental health among younger people. David Blanchflower of Dartmouth College, U.S., and colleagues present these findings in the open-access journal PLOS One on August 27, 2025.
Since 2008, a U-shaped trend in well-being with age, in which well-being tends to decline from childhood until around age 50 before rebounding in old age, has been observed in developed and developing countries worldwide. Data have also revealed a corresponding "ill-being" or unhappiness hump.
Recent data point to a worldwide decline in well-being among younger people, but most studies have not directly addressed potential implications for the unhappiness hump. To help clarify, Blanchflower and colleagues first analyzed data from U.S. and U.K. surveys that included questions about participants' mental health. U.S. data included responses from more than 10 million adults surveyed by the Centers for Disease Control and Prevention between 1993 and 2024. U.K. data spanned 2009 through 2023 and were collected in the ongoing U.K. Household Longitudinal Study, which involves 40,000 households.
The analysis showed that, in the U.S. and the U.K., the ill-being hump has disappeared, such that ill-being / unhappiness now tends to decline over the course of a lifetime. Ill-being among people in their late 40s and older did not change significantly. Instead, the hump's disappearance appears to be due to a decline in mental health among younger people.
Next, the researchers analyzed data on nearly 2 million people from 44 countries, including the U.S. and the U.K., from a mental health study called Global Minds. Covering the years 2020 through 2025, these data suggest the unhappiness hump has disappeared worldwide.
Reasons for the disappearance of the unhappiness hump are unclear. The authors suggest several possibilities, including long-term impacts of the Great Recession on job prospects for younger people, underfunded mental health care services, mental health challenges posed by the COVID-19 pandemic, and increased social media use. Further research is needed to determine whether any of these or other factors are at play.
The authors add: "Ours is the first paper to show that the decline in young people's mental health in recent years means that today, both in the United States and the United Kingdom, mental ill-being is highest among the young and declines with age. This is a huge change from the past when mental ill-being peaked in middle-age. The reasons for the change are disputed but our concern is that today there is a serious mental health crisis among the young that needs addressing."