If
you're what researchers call a short sleeper (i.e., you sleep for 5.5
to 6 hours or less a night), you'll have trouble losing weight, no doubt
about it. In a 7-year study of 7,022 middle-aged people, Finnish
researchers found that women who reported sleep problems were more
likely to experience a major weight gain (defined as 11 pounds or more).
You know that sleep and weight gain may be linked, but why is that?
Here's what the earth-shattering new research has revealed, and why lack
of sleep could be stalling your ability to lose weight and keep it off:
Sleep less, burn less. In a study at the department of
neuroendocrinology at the University of Lübeck, Germany, published in
the American Journal of Clinical Nutrition, researchers had a group of
men sleep for 12 hours a night but didn't allow them to sleep the next
night, and then had them eat an opulent buffet the following morning.
Then the researchers measured the subjects' energy expenditure-the
calories you burn just by being. When the men were sleep-deprived, their
general energy expenditure was 5 percent less than it was when they got
a good night's sleep, and their post-meal energy expenditure was 20
percent less.
Sleep less, eat more. In research presented at the American Heart
Association's 2011 Scientific Sessions, it was shown that women who got
only 4 hours of sleep at night ate 329 additional calories the next day
than they did after they slept 9 hours. (Men ate 263 calories more.) In
another study published in the American Journal of Clinical Nutrition,
11 volunteers spent 14 days at a sleep center on two occasions. During
one period, they slept 5.5 hours a night, and during the other, they
slept 8.5 hours. When the subjects were sleep-deprived, they increased
their nighttime snacking and were more likely to choose
high-carbohydrate snacks.
Sleep less, crave more. This is probably the biggest revelation
about the connection between sleep and weight loss-and the biggest
challenge for you if you're not getting at least 7 solid hours of sleep
each night. Sleeping too little impacts your hormone levels in ways that
can undermine the efforts of even the most determined dieter. That's
because insufficient sleep raises the levels of ghrelin, the hormone
that tells you to eat. When it comes to weight gain and loss, this
hormone plays a leading role.
Ghrelin's job is to boost your appetite, increase fat production, and
make your body grow-all of which are fine things if you're a lanky
12-year-old. But as you get older, ghrelin's effects can seem pretty
darned undesirable. It's a cinch to figure out why this hormone is the
last thing a dieter needs to have circulating in excess.
Lack of sleep also lowers levels of leptin, the hormone that says, "I'm
full; put the fork down." And leptin has a circadian rhythm all its own:
Leptin's levels run high during the night, which tells your body while
you're sleeping that you don't need to eat. Its levels drop during the
day, when you need food as energy. So high leptin levels keep hunger at
bay. In studies, for example, mice lost weight because leptin made them
eat less and exercise more: the holy grail of dieting. But if you don't
get enough sleep, your leptin levels plummet.
So after even one night of too little sleep, leptin and ghrelin become
dietary gremlins bent on diet-wrecking mischief. The lower leptin levels
mean that you still feel hungry after you eat. And ghrelin, for its
part, magnifies the problem by stimulating your appetite, setting the
stage for a day of unsatisfying, high-cal feasting after a restless
night.
In the Wisconsin Sleep Cohort Study of more than 1,000 people,
researchers found that people who got 5 hours of sleep a night had 15.5
percent lower leptin levels and 14.9 percent higher levels of ghrelin,
compared with those who got 8 hours of sleep. Know what else the
nonsleepers scored higher numbers in? BMI. So more ghrelin plus less
leptin equals greater body mass index and weight gain.
In a study at the University of Chicago, researchers discovered that
restricting the sleep of 12 healthy young men to 4 hours a night lowered
their leptin levels by 18 percent. The men rated themselves as having a
24 percent increase in hunger.
Sleep less, hang on to fat more. Lack of sleep may also affect the kind of weight you lose.
In another study at the University of Chicago, researchers followed 10
overweight but healthy subjects who were placed on a balanced diet, then
observed in two 14-day increments, one in which they got about 7.5
hours of sleep, and another in which they got 5 hours and 15 minutes.
During both periods, the subjects lost an average of 6.6 pounds. But
when they got more sleep, they lost 3.1 pounds of fat, whereas during
the short sleep period, they lost only 1.3 pounds of fat. Those who got
more sleep reported less hunger, which makes sense: When they got enough
sleep, their ghrelin levels stayed the same. On the 5-hour nights,
their ghrelin levels rose by 9 points.
Since ghrelin also promotes the retention of fat, researchers theorize
that a lack of sleep explains why the nonsleepers held on to body fat.
This happens because the diet-unfriendly hormone reduces the number of
calories you burn off and increases glucose production.
Sleep less, have more time to eat. It hasn't been scientifically
proven, but some experts believe that the 2 hours or more that we're no
longer using to sleep is giving us another 2 hours to raid the fridge.
Instead, get in that bed!
Arlington National Cemetery saw a great number of people visit to pay their
respects to service members killed in wartime on Memorial Day. But how much do you
know about the history of the cemetery? In 148 years, Arlington has
seen its share of scandals, including how it came to be where it is.
Seeing
things in black and white can make you more judgmental, literally! A new
study shows that people who look at things with black-and-white background
are less likely to see moral dilemmas:
Germany
has low unemployment, solid economic growth, and Oktoberfest ... but why
are Germans so grumpy? Perhaps they've lost the "Joy DNA," according
to researchers:
Tanning a hide and making buckskin shorts is hard work, and making
fire by rubbing sticks together is frustrating and tedious, but
participants say the result is a profound sense of understanding the
materials that you work with. Firefly co-founder Natalie Bogwalker
explained, “Firefly is here to stave off the amnesia of modern
technocratic culture…When normal people come here they are really
inspired and feel that things are possible…"
