Sleep Less, Eat More, Gain Weight

By Carrie Gann

Obesity linked to hormonal changes, lack of sleep

We’ve all heard about the importance of getting a good night’s sleep, and now scientists offer more evidence to back that up. A new study found that people who get less sleep may be inclined to eat more, move less and gain weight.

Scientists at the Mayo Clinic in Rochester, Minn., studied a group of 17 healthy volunteers between the ages 18 and 40 for a week in their homes, monitoring how much each one typically slept and ate. Then, they brought the volunteers into the clinic’s research lab for eight days: Half of the volunteers were allowed to sleep according to their usual pattern, and the other half got only two-thirds of their usual shut-eye.

All the volunteers were allowed to eat as much food as they wanted from the hospital cafeteria or from outside the research center. The researchers also measured how much energy each volunteer expended each day.

The sleep-deprived participants wolfed down an average of 549 calories beyond their usual intake but burned no more calories than their well-rested peers.

“A lot of people have this idea that if they’re up late, working hard, they’re burning more energy. But we found no change in how much they moved when sleep deprived,” said Dr. Andrew Calvin, lead author of the study and an assistant professor of medicine at the Mayo Clinic. “They’re consuming an additional 549 calories per day, but not burning any of them off.”

Those excess of unburned calories is a surefire way to gain weight, which numerous studies have connected to a variety of chronic health problems.

The volunteers who got less sleep also had higher levels of leptin, a hormone that suppresses appetite, and lower levels of ghrelin, a hormone that stimulates appetite, in their blood. The findings seem counterintuitive to what researchers would expect in people who are hungrier, but Calvin said the hormones were most likely an outcome, rather than a cause of people eating more.

Scientists have previously studied the physical downsides of getting too little sleep.

In 2011, Australian researchers found that adolescents and teenagers were more likely to be slimmer if they went to bed earlier, while those who stayed up late were more likely to engage in sedentary activities.

Previous studies have also found that workers covering late and overnight shifts were more likely to be obese and have type 2 diabetes, which may be associated with unhealthy eating habits, according to an editorial published in December.

The connection between sleep and weight may be important for the more than one-quarter of Americans who get six hours of sleep or less every night. Calvin said the future research on how sleep affects eating habits may give scientists useful insights into two of America’s biggest health problems: sleep deprivation and obesity.

“This study, while small, suggests that these two may indeed be linked, and if the findings are confirmed, they may suggest that sleep is a powerful factor in how much we eat and our chances of gaining weight,” he said.


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Warning Sign? Disrupted Sleep Tied to Alzheimer’s

By Stephanie Pappas, LiveScience Senior Writer

Warning Sign? Disrupted Sleep Tied to Alzheimer's

People who awaken more during the night are more likely than sound sleepers to have pre-clinical signs of Alzheimer's Disease.

Trouble sleeping in middle age could herald Alzheimer’s disease later in life, according to new research linking dementia and slumber.

The findings can’t yet prove whether disturbed sleep helps contribute to the brain changes that cause Alzheimer’s or whether some other factor links the two; but preliminary results suggest that treating sleep problems might be beneficial for the brain in the long run.

“If sleep is found to affect either the beginning or the progression of Alzheimer’s disease, especially in its early stages, then it’s really an attractive thing to try to manipulate, because getting more sleep or better sleep has really no risk,” said study researcher Yo-el Ju, an assistant professor of neurology at the Washington University School of Medicine in St. Louis.

Plaque in the brain

In 2009, Ju’s Washington University colleague David Holtzman published research in the journal Science reporting that depriving mice of sleep causes a 25 percent increase in the levels of a protein fragment called amyloid beta in the brain. Amyloid beta is the primary ingredient in the amyloid plaques that clog the brains of people with Alzheimer’s.

These mice were genetically engineered to accumulate amyloid beta, and mouse-brain chemistry may not always match that of humans. So Ju and her colleagues, including Holtzman, turned to a group of people enrolled in the Adult Children Study, so named because half of the volunteers in the study are children of parents with Alzheimer’s.

They recruited 100 volunteers ages 45 to 80, all of whom had been clinically tested and showed no signs of memory loss or cognitive decline. The volunteers wore a wristwatch-like device called an actigraph for two weeks. The device measures activity levels, which can then be translated into time asleep and time awake. [Top 10 Spooky Sleep Disorders]

“Other studies that have looked at the relationship between sleep and dementia have generally studied older individuals who are obviously at higher risk of dementia, so I think this study is important because we’re looking at a population that is much younger,” Ju said.

Sleep and dementia

The results revealed that people who spent more of their time in bed tossing and turning rather than sleeping were more likely to show abnormal levels of chemicals that indicate amyloid beta. These chemical markers show up 10 or 15 years before any sign of memory loss or decline, but almost everyone who has them will eventually develop Alzheimer’s if they don’t die of something else first. About 25 percent of the people in the study fell into this “preclinical Alzheimer’s” category.

People who woke up more than average — or more than five times every hour — were also more likely to show signs of amyloid beta accumulation. Participants didn’t necessarily remember these waking periods the next morning, Ju said.

Ju and her colleagues will present their results at the American Academy of Neurology’s 64th annual meeting in New Orleans, which begins April 21. The study has not yet been published in a peer-reviewed journal. In the meantime, they’re continuing the sleep studies on more volunteers. In the long term, Ju said, the researchers hope to find out what causes the troubled sleep in people with preclinical Alzheimer’s.

“These are pretty preliminary results, and although they are intriguing and promising, we really need to do longer-term studies to find out which direction this is going,” Ju said.


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