Are healthy habits worth the outcome?


Q: How might you assess the true cost of your health habits? Exercise? Alcohol consumption? Cigarette smoking? Eating fruits and vegetables? Being a couch potato?

A: By checking their effect on your longevity, as measured in "microlives," a term coined by Professor David Spiegelhalter of the University of Cambridge, where 1 microlife, or one-millionth of a person's life expectancy, equals a time interval of roughly 30 minutes, says Mark Fischetti in "Scientific American." Based on Spie gelhalter's analysis of health tables for a variety of behaviors, he determined, statistically speaking, smoking two cigarettes subtracts 1 microlife (30 minutes) from your life, while one serving of fruits and vegetables adds about 1 micro life. Alcohol consumption is a mixed bag: The first drink (10 grams of alcohol) of the day benefits the boozer by 1 microlife, but each two additional drinks subtracts 1.

From this perspective, the benefits of exercise are intriguing: The first 20 minutes of moderate exercise (brisk walking or bicycling) adds 2 microlives (60 minutes). But the next 40 minutes adds only 1 microlife (30 minutes), a net loss in that more time is spent exercising than is gained in life expectancy. For all you couch potatoes, though, it's unambiguous: two hours of sitting without activity subtracts 1 microlife.

Q:In life's "what if" category, how was another "giant leap for mankind" almost lost by a man's near misstep?

A: NASA astronaut Leroy Chiao flew four space missions over a 15-year career, including serving as Commander of the International Space Station, as he told "Mental Floss" magazine. He spent nearly 230 days in space and performed six spacewalks.

Yet these have nothing to do with Chiao's "most horrifying and exhilarating near-death experience." Only days after realizing his boyhood dream of being chosen as a NASA astronaut, he stood on a busy San Francisco street corner when the light turned green and a WALK signal lit up. As Chiao described it, "I sensed that something wasn't right and paused for just a moment. As I started to look to the left, a double Muni bus passed by ... in a blur, and the mirror missed my head by mere inches. Had I taken even a half-step off the curb, the mirror would have struck me, and it would have been fatal. Selected to be an astronaut and then hit by a bus. How ironic would that have been?"

Q:Why are so many people these days developing "myopia," or nearsightedness? For this one, there are theories stretching practically as far as the eye can see.

A:Nearsightedness has increased steadily in North America and Europe in recent decades, with one-third of adults in the U.S. now nearsighted, says Nathan Seppa in "Science News" magazine. From the early 1970s to the turn of the century, myopia prevalence in the U.S. rose from 25 percent to nearly 42 percent among those aged 12 to 34, a substantial shift in a single generation. For some reason, such increases have not shown up in older generations nor in people living in rural areas.Studies linking myopia to limited time spent outdoors during childhood first surfaced a few years ago, taking many researchers aback. Still, the evidence is far from clear: Some scientists say the benefit could come from exposure to natural light, or a relaxation of the eye gained from viewing things at a distance, or the visual tableaux the eye encounters outdoors. Or it could be a mix of all three. Or is it because of a whole generation raised on computers, video games, and excessive "near work" in school. The "maybe" debate goes on.

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