Health & Science

Why so many of us are tired

It’s a national epidemic of fatigue: About 60 percent of Americans report that most of the time, they don’t get a good night’s sleep. A survey by the National Sleep Foundation of more than 1,000 people between ages 25 and 60 found that the average American gets between six and seven hours of sleep on weeknights, leaving them feeling chronically tired. “Most people require seven to nine hours of sleep to feel rested,” Thomas J. Balkin, chairman of the foundation, told CNN.com. “Sleepiness impacts every aspect of our lives.” One in four people surveyed said they’d missed work or a family event because they’d been too tired to function; one in four said they were too exhausted most nights to have sex. The cause in most cases, researchers said, was poor “sleep hygiene.” Sleep can be disturbed by such practices as making big changes in bedtimes and waking times, which confuses the body’s internal clock; excessive worry and anxiety; and being too busy right up to bedtime, instead of spending the last hour of the day winding down. The survey found that 75 percent of African-Americans and 64 percent of whites routinely watch TV right up to bedtime, with another 20 percent going online—activities that experts say may be too stimulating. The benefits of changing these bad habits and thus getting better rest, Balkin says, include clearer thinking during the day, more energy, and “a better quality of life.”

Fastest tongue in the West

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In pursuit of tasty insects, a chameleon fires its tongue with explosive force, with more than 10 times the acceleration of the Space Shuttle. More impressive still, says LiveScience.com, the coldblooded lizard maintains the speed of its lightning-fast tongue even when temperatures drop and the rest of its muscles become sluggish. University of South Florida researchers used a high-speed camera to film chameleons feeding in a range of temperatures. They found that the lizard’s amazing tongue—which coils inside like a spring and can extend to twice the creature’s body length—explodes outward with 41 G’s of force. By way of perspective, the Space Shuttle produces only about three G’s on its fiery takeoff. But what really surprised researchers was that reducing the temperature by 18 degrees Fahrenheit—which made the chameleons move slowly—had only a small effect on their tongues’ speed. This adaptation, says researcher Chris Anderson, enables chameleons to feed in the early morning and in the evening, when rival predators may be inactive. “Most lizards are unable to forage effectively at low temperature,” he says.

Women who drink are slimmer

Women who drink lightly or moderately appear to gain less weight in midlife than nondrinkers do, says a new study. Researchers at Brigham and Women’s Hospital in Boston examined health data from 19,000 women over 13 years, and found that those who did not drink at all gained the most weight over that period. Women who consumed a drink or two a day were 30 percent less likely to become overweight, with red wine drinkers showing the most benefit. (The effect did not hold true with men.) Why? Researchers don’t really know, but they theorize that because women have to work harder to metabolize alcohol, their digestive systems actually burn more calories than they consume in a glass of wine or beer. A more plausible explanation is that moderate drinking doesn’t cause weight loss, but instead is associated with socioeconomic and lifestyle factors that keep the pounds off. In the study, women who drank had greater levels of physical activity, were more likely to smoke, and ate less in general. So taking up drinking—or drinking more—probably won’t help women lose weight, warns University of North Carolina psychiatrist Dr. James Garbutt. “If the message is that by drinking alcohol you’re going to lose weight,” he says, “that’s a potentially complicated and dangerous message.”

Captain—you killed the crew

In Star Trek, the Starship Enterprise traverses vast interstellar distances by going into “warp speed.” But even if it were possible, there’s a problem with whizzing through space at close to the speed of light, says John Hopkins University physicist William Edelstein: It would kill everyone on board. In a new study, Edelstein examined what would happen if a spaceship of the future could attain 99 percent of the speed of light. At that speed, the stray hydrogen atoms drifting in the near-vacuum of space would smash into the ship at such speed and in such numbers that protons would be stripped from the atoms and pass through the metal and the bodies of crewmen inside. A fatal dose of radiation for humans is six sieverts, Edelstein tells Space.com, but his calculations show that on a ship traveling at “warp speed,” the crew would receive 10,000 sieverts per second. Star Trek fans have protested his conclusion, saying that the Enterprise’s electromagnetic “shields” could block such radiation. But Edelstein doubts that it’s possible to construct a shield that could block subatomic particles, and says for that reason, extraterrestrial visits to Earth are extremely unlikely. “Getting between stars is kind of impossible, based on what we know right now,” he says.