sleep

Your deep brain doesn't know that your hotel isn't full of hungry hyenas waiting to pounce.

Half Your Brain Stands Guard When Sleeping In A New Place (NPR.org)

When you sleep in unfamiliar surroundings, only half your brain is getting a good night's rest.

"The left side seems to be more awake than the right side," says Yuka Sasaki, an associate professor of cognitive, linguistic and psychological sciences at Brown University.

The finding, reported Thursday in the journal Current Biology, helps explain why people tend to feel tired after sleeping in a new place. And it suggests people have something in common with birds and sea mammals, which frequently put half their brain to sleep while the other half remains on guard.

From Yahoo! News: Sleep Is Important to Weight Loss, Research Suggests

In common weight-loss advice, "get more sleep," should figure just as prominently as "eat less" and "move more," two researchers in Canada argue.

...

The researchers pointed to a 2010 study in which participants were randomly assigned to sleep either 5.5 hours or 8.5 hours every night for 14 days. They all cut their daily calorie intake by 680 calories, and slept in a lab. Participants who slept for 5.5 hours lost 55 percent less body fat, and 60 percent more of their lean body mass than those who slept for longer.

In other words, the sleep-deprived people held onto their fat tissue, and instead lost muscle.