Research: Belly fat disrupts sleep quality
Dropping extra pounds enhances the quality of sleep among people who are overweight, according to a new study by researchers at Johns Hopkins University in Baltimore.
“We found that improvement in sleep quality was significantly associated with overall weight loss, especially belly fat,” says Dr. Kerry Stewart, professor of medicine at the Johns Hopkins School of Medicine and senior author of the study, which was presented at the American Heart Association Scientific Sessions in November.
The six-month study followed 55 overweight volunteers who had Type 2 diabetes or prediabetes. Researchers used surveys to track the participants’ sleep quality and divided them into two groups. One group dieted and exercised while the other group just dieted. Members of both groups lost an average of about 15 pounds and approximately 15% of belly fat. In addition, both groups improved their overall sleep score by about 20%.
“The key ingredient for improved sleep quality from our study was a reduction in overall body fat, and, in particular belly fat, which was true no matter the age or gender of the participants or whether the weight loss came from diet alone or diet plus exercise,” Stewart says.
Sleeplessness wreaks havoc on fat cells
Sleep isn’t just for the brain, concludes a study from the University of Chicago, which found that not getting enough shut-eye is harmful to fat cells, reducing by 30% their ability to respond to insulin, a hormone that regulates energy.
The research, published in the Oct. 16 issue of the Annals of Internal Medicine, connects sleep loss to the disruption of a person’s ability to regulate energy, a process that can lead to weight gain, diabetes and other health problems. The study suggests that sleep’s role in energy metabolism is at least as important as it is to brain function.
“We found that fat cells need sleep to function properly,” says study author Matthew Brady, associate professor of medicine at the University of Chicago. “Many people think of fat as a problem, but it serves a vital function. Body fat stores and releases energy.”
The two-part study included six men and one woman. In one part of the research, volunteers spent 8.5 hours a night in bed for four consecutive nights. In the other part, they spent 4.5 hours in bed for four nights. After the fourth night, researchers tested each participant’s total-body insulin sensitivity.
During the shortened sleep cycles, the insulin sensitivity of fat cells decreased by 30%—comparable with the difference between the cells of obese and lean people. Researchers also found that the sleep-deprived participants had a decreased response to insulin.
“Some people claim they can tolerate the cognitive effects of routine sleep deprivation,” says study co-author Eve Van Cauter, the Frederick H. Rawson Professor of Medicine at the University of Chicago. “In this small but thorough study, however, we found that seven out of seven subjects had a significant change in insulin sensitivity. They are not tolerating the metabolic consequences.”
Study: Sleep is indicator of pro athletes’ longevity
According to sleep researcher W. Christopher Winter, there’s a link between a pro athlete’s longevity with a team and the degree of sleepiness experienced during the day.
At last summer’s Sleep 2012, an annual meeting sponsored by the American Academy of Sleep Medicine and the Sleep Research Society, Winter presented two studies that associate the career spans of baseball and football players with their voluntary answers on a sleep questionnaire. The results show that less sleepy football players tended to remain with their drafting National Football League teams after college. Results were similar for Major League Baseball players.
Winter, medical director of the Martha Jefferson Sleep Medicine Center in Charlottesville, Va., says these studies show sleep evaluation can be a powerful tool for professional sports teams to determine a prospective athlete’s stamina and wellness.
The football study looked at 55 randomly selected college players who landed in the NFL, finding that sleepier athletes had only a 38% chance of staying with the team that originally drafted them. By comparison, 56% of the less-sleepy players were considered a “value pick” because they remained with the original team.
The baseball study analyzed the sleepiness of 40 randomly selected players and found that those who reported higher levels of daytime sleepiness had attrition rates of 57% to 86%, well above the 30% to 35% MLB average.
Dangers of sleep loss continue to mount
Lack of sleep is not only hazardous to an individual’s health—causing foggy-headedness, grumpiness and impaired judgment—sleep loss also can pose safety risks to entire cities and regions, even ecosystems.
In the article, “Coping with Excessive Sleepiness: 10 Things to Hate about Sleep Loss” posted recently on WebMD.com, Camille Peri pointed out the role sleepiness has played in accidents: “Sleep deprivation was a factor in some of the biggest disasters in recent history: the 1979 nuclear accident at Three Mile Island, the massive Exxon Valdez oil spill, the 1986 nuclear meltdown at Chernobyl and others.”
Among other things to hate about sleep loss: lack of sex drive, health problems, depression, forgetfulness, weight gain and aging skin.
Dolphins can go 15 days without sleep
Dolphins are able to remain awake and alert for long periods because they sleep with one half of their brains, according to research published Oct. 17 in the online science and medical journal Plos One.
Researchers from the National Marine Mammal Foundation found that dolphins can use echolocation, a type of biological sonar, with near-perfect accuracy continuously for days, identifying targets and monitoring their environment.
Studying two dolphins—one male and one female—scientists discovered the dolphins were capable of using echolocation with no signs of fatigue for five days. The female dolphin performed additional tasks for a 15-day period.
The ability to sleep with only half the brain at a time (called unihemispheric sleep) is believed to have evolved in dolphins to enable them to breathe at the water’s surface, even when half-asleep. The new research suggests that the need to remain vigilant also may have played a role in the evolution of this sleeping behavior.