Forget, for a moment, how old you really are. The question is: How old do you feel?

Most of the 516 older people (70 and onward) who answered that question in a study just published by researchers at the University of Michigan and the Max Planck Institute for Human Development in Berlin said they felt about 13 years younger than their chronological age.

They also thought they looked younger than their actual years. The average response, when volunteers were asked, “How old do you feel when you look at yourself in the mirror” was ten years younger than their real age. In general, women were more realistic about how they looked than men. “Women saw themselves as about four years older than their male peers,” reported Jacqui Smith, a psychologist at the University of Michigan Institute for Health Research, who co-directed the study. That may partly explain why, at the beginning of the six-year investigation, men were more satisfied than women with how they were aging. As they study wore on, however, thet gap between the sexes narrowed.

Kidding yourself about age isn’t just a case of vanity. It may be good for your health. Other studies have shown that people who feel younger than their chronological age stay healthier and live longer than their more realistic counterparts. Indeed, it’s usually only when people develop health problems that the gap between perceived age and real age begins to narrow.

In a 2005 study, for example, Finnish researchers interviewed 395 men and 770 women between 65 and 84 years old. When asked about their perceived physical age, 37 percent said they felt younger, 11 percent older, and 52 percent the same as their chronological age. When asked about their mental age, 57 percent reported feeling younger, 5 percent older, and 38 percent the same as their real age. Those who described themselves as physically younger than their real age were half as likely to die during this 13-year study as those who felt older. Perceptions of physical age were stronger predictors of mortality than mental age.

Lucille Ball famously quipped, “The secret of staying young is to live honestly, eat slowly, and lie about your age.” She may have been more right than she realized.

So how old do you feel? Your answer could be a surprisingly sensitive gauge of your health and longevity.

Tags: chronological age, longevity, peceived age