Most adolescents can get by with at least eight hours of zzzzz’s a night, studies show, but ideally should garner at least nine. A new study tells us just how many kids meet their ideal slumber quota: a whopping 7.6 percent.
Roughly one-quarter of the kids fell into the borderline-acceptable category, meaning they reported eight hours of shuteye nightly. The overwhelming majority fell short — with 30.2 percent reporting seven hours, 22.8 percent slumbering closer to six hours, 10 percent catching a mere five hours of sleep, and 5.9 percent claiming to nod off for no more than four hours most weeknights. Just the thought makes me yawn.
What the study didn’t explore is why kids aren’t sleeping enough. Certainly, schools don’t help the situation by starting classes earlier for teens than they do for younger kids — even though puberty and other developmental changes lead to adolescents needing more sleep than grade schoolers, not less.
Like what share of teens don’t get enough sleep because they’re naturally night owls (like me) and find almost anything before 2 or 3 a.m. more interesting than slumber? Or what share suffer from a recurrent resetting of their biological clocks from exposure to night-time exposure to blue light — including that spooky glow given off by computer screens — so that their bodies no longer recognize when it’s bedtime? Or do today’s teens so drug themselves with caffeine to stay alert while doing homework that when it’s over they can’t immediately nod off?
Insufficient sleep impairs learning, impulse control, and judgment. It appears to even predispose people to disease. Indeed, one motivation for the survey was to probe kids’ behaviors and the extent to which these might help explain four leading causes of death among 10- to 24-year olds: motor-vehicle crashes, other unintentional injuries, homicide and suicide
Even a day’s sleepiness, recent studies have shown, can perturb hormone concentrations in the body in ways that not only foster hunger, but also can encourage the preferential use of calories to produce body fat, not heat and energy. And not surprisingly, 29 percent of the students in this study were overweight, if not obese. Other studies have also observed that kids who sleep less tend to be heavier.
If we want to find ways to encourage healthy habits, we need to understand what the obstacles to them are. And this new study certainly jolts us awake as to the magnitude of our kids’ potentially risky sleep deficits.
CONCORD, N.H. - Even after five years, Christy Pugh has no trouble sticking to her vegetarian regimen.
The secret to her success? Eating meat.
“Sometimes I feel like I’m a bad vegetarian, that I’m not strict enough or good enough,” the 28-year-old bookkeeper from Concord said recently. “I really like vegetarian food but I’m just not 100 percent committed.”
Pugh is one of a growing number of part-time vegetarians whose loose adherence to the meat-free diet is transforming a decades-old movement and the industry that feeds it.
'I really like sausage' These so-called “flexitarians” — a term voted most useful word of 2003 by the American Dialect Society — are motivated less by animal rights than by a growing body of medical data that suggests health benefits from eating more vegetarian foods.
“There’s so many reasons that people are vegetarians … I find that nobody ever gives me a hard time when I say I usually eat vegetarian. But I really like sausage,” Pugh said.
In recent years the market for vegetarian friendly foods has exploded, with items such as soy milk and veggie burgers showing up in mainstream groceries and fast food restaurants.
But even the diet’s activists say that growth can’t be attributed to committed vegetarians, who are estimated at about 3 percent of the adult U.S. population, or about 5.7 million people never eating meat, poultry or seafood.
Charles Stahler, co-director of the Baltimore-based Vegetarian Resource Group, credits the growth to flexitarians — vegetarians who dabble in meat and carnivores who seek out vegetarian meals.
“This is why Burger King has a veggie burger. It’s not because of us,” he said. “The true vegetarians wouldn’t rush to Burger King anyway. It’s because of those people in the middle. They are the driving audience.”
Though flexitarian headcounts are imprecise, Stahler estimates roughly 30 percent to 40 percent of the population at least occasionally seeks out vegetarian meals.
Room for flexibility Suzanne Havala Hobbs, a nutrition professor at the University of North Carolina at Chapel Hill, credits the growth of flexitarianism to the nation’s better understanding of the diet-disease connection.
“Whether you make a commitment to eating strictly vegetarian or not, cutting back your dependence on meat is something most people acknowledge they know they should do,” she said.
Mollie Katzen, a cookbook author and a founder of the iconic vegetarian eatery Moosewood Restaurant in Ithaca, N.Y., takes another perspective. The former vegetarian thinks people who eschew meat would be better off if they didn’t.
Though she still advocates vegetable-based diets, Katzen sees room — and for many people a need — for flexibility.
“To base our diet there, yes. Absolutely,” she said. “However, where the protein comes from in that diet, I don’t feel it’s wrong if you’ve got a great big plate of vegetables your protein is from a healthy, happy chicken, or a grass-fed cow.”
Plenty of people seem to agree. At Wild Oats stores, a Boulder, Colo.-based chain of natural foods grocers that cater to vegetarians, the majority of shoppers aren’t vegetarians.
Tracy Spencer, a spokeswoman for the company, said Wild Oats shoppers are concerned about health and want the grocer’s natural and organic products, including meats.
Publishers take notice Publishers of vegetarian magazines also are taking notice. To target the part-timers many have softened their approach to meatless diets, even at risk of alienating the far smaller reader pool of true vegetarians.
Until last year Natural Health, a Woodland Hills, Calif.-based magazine with a monthly circulation of 300,000, published only vegan recipes, which exclude even dairy and honey.
Now the recipes regularly include meat, said Barb Harris, the magazine’s editorial director.
“There is a big interest in vegetarianism,” she said. “But we can also tell from our readership that these are not people who are following a pure vegetarian lifestyle. These are people who are integrating a vegetarian menu in their current diets.”
A similar change occurred at the 30-year-old Vegetarian Times, considered the standardbearer of vegetarianism. Though still meat-free, the once mostly vegan magazine focuses less on activism and more on recipes with broader appeal.
Carla Davis, managing editor of the Glen Allen, Va.-based monthly, said the changes were made after a survey showed 70 percent of the magazine’s 300,000-plus readers weren’t vegetarian.
Even the strictest of vegetarian advocacy groups considers the flexitarian trend a good thing.
Bruce Friedrich, spokesman for Norfolk, Va.-based People for the Ethical Treatment of Animals, said he doesn’t see any harm in vegetarianism focusing more on food than the issues that spurred the movement.
“From our perspective, if people influenced by health consequently cut back on fish and meat consumption, that helps animals,” he said. “If two people cut their meat in half it helps as much as one person going completely vegetarian.”
The air pollution emitted by cigarettes is 10 times greater than diesel car exhaust, a small Italian study finds.
Researchers compared the particulate matter in the exhaust fumes from a modern car engine, fuelled with low-sulphur diesel, and in cigarette smoke. Three smouldering cigarettes produced a 10-fold increase in air particles compared to those produced by the idling vehicle.
"I was very surprised. We didn’t expect to find such a big difference in the particulate matter produced," says Giovanni Invernizzi from the Tobacco Control Unit of Italy’s National Cancer Institute in Milan, who led the study.
Ivan Vince, an air pollution expert from Ask Consultants in London, UK, says the findings are reasonable. He notes that cigarettes give off a lot more respirable particulates than the new generation of low-sulphur diesels, which help cut particulate emissions.
Invernizzi and colleagues conducted their controlled experiment in a private garage in the small Alpine town of Chiavenna, which enjoys a particularly low level of air pollution.
The car used was 2002 Ford Mondeo turbo diesel with a two-litre engine, and had been on the road for six months. It was left idling in the closed garage for 30 minutes while a portable analyser took particulate air samples every two minutes.
The garage was then aired for four hours, after which the doors were re-closed and three filter cigarettes were burned sequentially over a total of 30 minutes.
The portable analyser showed that 10 times as many pollutant particulates were released in the cigarette smoke as the diesel fumes. And the comparative pollution levels for the tiniest particulates - the most dangerous to health - were even greater.
"The tiny particulates, less than 2.5 micrometres, are able to penetrate right into the alveoli in the lungs, where the carcinogens do the most damage," Vince says.
"Most of the chemicals emitted from cigarettes are very short-lived and so they mostly damage the local environment. For example, aldehydes damage plants and peoples’ eyes and respiratory tract," he notes. Nitric oxide, also produced by cigarettes, is the culprit in photochemical smog and drives ozone formation in cities.
"But with more and more people being made to smoke outside and in doorways, the external environmental effects must surely rise," Vince told New Scientist.
Invernizzi is hoping his results will provide a new weapon in the fight against teenage smoking. “Adolescents in Milan campaign against pollution and for a better environment - often with a cigarette hanging out of their mouths. We can show them that smoking also harms the environment.”
Journal reference: Tobacco Control (vol 13, p 219)