A new study from Japan suggests that people may have a better sense of their own longevity than expected. Researchers found a clear link between how long older adults believed they would live and how long they actually survived. But there was an important twist: many participants underestimated their own longevity. About 59% lived beyond the age they had predicted, suggesting that people may be better at judging their relative lifespan than pinpointing an exact age of death.

The findings come from researchers led by Shohei Okamoto of the University of Tsukuba, who analyzed long-term data from the Japanese Aging and Health Dynamics Study. The research followed older adults for up to 28 years. The study was posted as a preprint on medRxiv on August 28, 2026, meaning it has not yet undergone peer review.

How accurate are people at predicting when they will die?

The researchers examined responses from older adults in Japan who were asked how old they expected to live to be.

The analysis began with roughly 2,000 participants who provided information about their expected lifespan. Participants gave a specific age or, in some cases, said they did not know.

The researchers then compared those expectations with subsequent mortality records and estimates of actual lifespan. Among the participants whose outcomes could be established, subjective life expectancy was significantly associated with actual longevity.

In other words, people who expected to live longer generally did live longer than those who expected a shorter life.

That does not mean people possess some kind of biological countdown clock. Instead, their estimates may reflect information they already have about their health, lifestyle, family history and social circumstances.

Why did so many people underestimate their lifespan?

The most striking finding was the direction of the error.

Around 59% of participants outlived the age they had expected to reach. This means the larger problem was not widespread optimism, but underestimation of how much time they had left.

Researchers say several factors could help explain the pattern. A person who feels physically healthy, has relatives who lived to advanced ages or has a stronger socioeconomic position may naturally expect a longer life.

The study also found differences linked to sex and education. Women and people with higher levels of education were more likely to outlive their own estimates.

These factors do not prove that education or optimism directly extends life. They may instead influence how people assess their health and future prospects.

Why was 80 such a popular answer?

One number stood out in the responses: 80.

Researchers noted that many participants selected ages such as 80, which was close to Japan’s combined-sex life expectancy at birth around the time some of the survey data were collected.

That could mean respondents were not making highly personalized predictions at all. Instead, some may have unconsciously anchored their answers around a familiar population statistic.

This is known as an anchoring effect, where an easily available number influences judgment even when a person is trying to make an individual estimate.

The researchers also found that participants with more education were less likely to give rounded ages ending in zero or five, such as 75, 80 or 85. That suggests some respondents may have been making more individualized estimates while others relied on convenient benchmark numbers.

Does believing you will live longer actually make you live longer?

Not necessarily.

The association between life expectancy predictions and actual survival is interesting, but it does not establish that positive thinking itself extends lifespan.

Because the study is observational, researchers cannot determine whether expectations caused differences in longevity. A long list of underlying factors could influence both a person’s expectations and their eventual survival.

For example, someone who believes they will live to 90 may already have better health, stronger social connections, better access to medical care or healthier habits. Those characteristics could help explain both the optimistic prediction and the longer life.

So the study should not be interpreted as evidence that simply thinking positively can add years to a person’s lifespan.

What does the study actually tell us?

The research offers a more nuanced picture of how people understand their own mortality.

People appear to have some meaningful information about their future longevity, since their expectations were statistically linked to actual survival. At the same time, their estimates were far from exact, with many people living longer than they had anticipated.

That combination is perhaps the most revealing finding. Human beings may be reasonably good at sensing whether they are likely to live relatively longer or shorter lives, while still being poor at predicting the precise age at which they will die.

The findings could also matter beyond curiosity. Researchers studying aging often rely on objective indicators such as medical conditions, mortality risk and demographic characteristics. A person’s own expectation of survival may provide another piece of information about how they perceive their health and future.

Study status

The research, titled “Expecting the unexpected: Subjective life expectancy and actual mortality,” is currently a medRxiv preprint and has not yet been peer-reviewed. Its conclusions should therefore be treated as preliminary rather than definitive.