Middle age is fascinating because it’s one of the most mysterious points in the human lifespan. Researchers have studied youth and old age relentlessly, but they have largely overlooked middle age. Funnily enough, we even struggle to define when middle age begins.
A 2026 YouGov poll found that most people see it happening in their 40s, with 49% saying it happens from 40 to 49. Thirty-three percent say it occurs in their 50s. If you want to be technical, the average person lives to 79, so 39.5 is the exact middle age.
What are some misconceptions about being middle-aged?
Margie Lachman, PhD, the Director of Lifespan Development at Brandeis University, suggests that we see midlife more as a state of mind, or better yet, a slate of responsibilities than an actual age. “Well, for the most part, we’re talking about the 40s and 50s,” Lachman told the American Psychological Association’s Speaking of Psychology podcast.
“But what might surprise you is that it’s really not about the number of candles on your birthday cake. It’s really something related to the central roles that people play in midlife,” Lachman continued. “So it’s the sandwich generation. When you’re caring for your kids while also helping your aging parents, you’re literally in the middle and pulled in both directions. So that’s what I think of as the essence of midlife. It’s less about the chronological age and more about your unique and challenging position.”
In Lachman’s new book, Primetime: A New Vision for Midlife, she illustrates one of the greatest misconceptions about middle age: most people see it as a time of stability, but many experience dramatic changes in their careers, family dynamics, and sense of self. It’s also a time when people can make big changes they may not have considered because of developmental stereotypes about people in their 40s and 50s.
“It really is only relatively recently that even psychologists believe that personality can change,” Lachman said. “There was this notion for many years that personality was set in stone or set like plaster and that we really couldn’t make changes. But indeed there’s been research more recently that shows that people can change naturally just by aging.”
Which personality traits are associated with longevity?
Lachman says that people who rank high in conscientiousness are most likely to thrive in the second half of their lives. Conscientiousness is one of the Big Five personality traits and is associated with being responsible, well-organized, hard-working, goal-oriented, and able to adhere to norms and rules. “And these are the people who have the best health, and they live longer,” Lachman said. “So a number of longitudinal studies have shown high conscientiousness leads to much better health outcomes and even longer life.”
Ultimately, Lachman believes that although middle age comes with challenges, we should focus on the positive growth many people enjoy at this stage of life. “So I would say it’s important to choose a positive mindset,” she continued. “There’s a lot of research out there by others and our work as well that show that negative attitudes about aging are really harmful and negative attitudes about your ability to carry out your everyday tasks, thinking that all the changes that are associated with aging, it’s all downhill, rather than focusing on all the positive things like gains in confidence, gains in self-esteem.”
