How long do you expect to live? A new long-term study of older adults in Japan suggests that many people have a surprisingly good instinct for their own lifespan, even if their estimates are far from perfect. Yet one clear pattern emerged: most participants actually lived longer than they predicted.
Researchers found that about 59% of people in the study outlived their own expectations. The work, led by Shohei Okamoto of the University of Tsukuba, draws on data from the Japanese Aging and Health Dynamics Study, a large, nationally representative survey that has followed older adults for nearly three decades.
How the study was conducted
In 1996, 2,447 Japanese adults aged 60 and older were asked a simple question: What age do you expect to live to? Of those participants, 393 said they did not know, while 2,054 provided a specific age ranging from 63 to 120. Their answers provided the basis for a rare long-term examination of how accurately people perceive their own longevity.
Over the following 28 years, 1,514 participants who had provided an estimate died. For approximately 98% of these deaths, researchers obtained precise dates from official resident records or reports from family members. This allowed them to compare each participant’s predicted age at death with their actual lifespan.
Expectations and real lifespans
People who believed they had more years ahead of them generally did live longer. The association between expected and actual lifespan remained even after researchers adjusted for age, sex, income, education and several measures of health. The findings suggest that people’s expectations contain meaningful information about their health and life circumstances.
However, the effect was modest. In the researchers’ model, each additional year of expected life corresponded to only about 0.12 additional years of actual survival on average. In other words, expecting to live 10 years longer was associated with roughly 1.2 additional years of observed life rather than an entire decade.
The predictions were also systematically biased. Most participants underestimated how long they would live, contributing to the 59% who outlived their expectations. Women and people with more years of education were particularly likely to live beyond their predicted age, while participants in poorer health were less likely to do so.
Anchoring on the age of 80
One clue to this pattern can be found in a familiar number: 80. Many participants selected 80 as their expected age at death despite substantial differences in their current age and health. This closely matched Japan’s combined life expectancy at birth in the mid-1990s, suggesting that respondents may have anchored their estimates to a widely known population average.
However, life expectancy at birth is different from the remaining life expectancy of someone who has already reached an older age. A person who reaches 70, for example, has already survived earlier-life risks that contribute to the national average. Actuarial estimates would therefore typically give such an individual several additional expected years beyond the figure commonly reported at birth.
The researchers also identified a subtle effect of education. Better-educated participants were less likely to choose rounded ages such as 75, 80 or 85 and were more likely to provide less tidy numbers. Yet these apparently more precise predictions were not more accurate, and underestimating lifespan remained common.
Does optimism extend life?
The findings raise an intriguing question: Can believing that you will live longer actually help you survive longer? The researchers caution against drawing that conclusion. Because the study was observational, it cannot establish that positive expectations cause longer life, only that the two are associated.
Instead, people may draw on a combination of conscious and unconscious information about their health, habits and family history when estimating their lifespan. Someone who feels physically well, has few chronic conditions and comes from a long-lived family may reasonably expect to live longer and may ultimately do so.
Although the researchers adjusted for several health factors, they acknowledge that unmeasured characteristics such as resilience, lifelong nutrition or quality of medical care could influence both expectations and survival. The study therefore cannot determine how much of the observed association might be related to mindset itself.
Why misjudging life expectancy matters
Mistakes in estimating personal lifespan are more than a psychological curiosity. The authors argue that underestimating longevity could contribute to poorly planned retirements, with people saving too little or spending their savings too quickly. Overestimating lifespan, meanwhile, could lead to unnecessary frugality or financial difficulties later in life.
Japan’s rapidly aging population makes these questions particularly important, but similar concerns apply to many countries experiencing rising life expectancy. As societies increasingly shift from traditional pensions toward individual savings and investment accounts, realistic estimates of longevity become more important for household financial planning.
The researchers suggest that governments and financial advisers could support better decisions by providing clearer, age-specific information about remaining life expectancy that accounts for sex and current age rather than relying on a single headline figure for the entire population.
Limits and broader implications
The study has several important limitations. Participants estimated their lifespan only once, in 1996, so researchers could not determine how major life events, medical diagnoses or bereavements might have changed their expectations over time.
The dataset also lacked detailed information about parental longevity, which can influence both perceived and actual lifespan. In addition, all participants were older Japanese adults, meaning the findings may not apply directly to younger people or populations with different healthcare systems and cultural attitudes toward aging.
The study has been posted as a preprint on medRxiv and has not yet undergone peer review. Its methods and conclusions therefore still need to be evaluated by other experts. Nevertheless, the research adds to a growing body of work examining subjective life expectancy and how people use their internal sense of health and risk when planning for the future.
Overall, the results suggest that people possess useful, although imperfect, insight into their own longevity. Their predictions appear to reflect genuine information about health and circumstances, but they often overlook one possibility: life may last longer than they expect.