All-Nighters Make Bodies Hoard Calories

"Staying up all night clearly taxes the body, but scientists have only now added up the exact bill. By measuring the actual number of calories the body expends to fuel an all-nighter versus a good night's sleep, researchers from the University of Colorado at Boulder calculate that a full night of sleep helps the body conserve as much energy as is in a glass of warm milk.

Missing a night of sleep forces the body to burn about an extra 161 calories than it would have during eight hours of sleep (not counting what's used in moving around while awake), but it's no weight-loss miracle: The body tries to make up for the deficit by saving more energy than usual the next day and night, researchers report in the January Journal of Physiology.

The measurements, the first to put precise numbers on how much total energy people use in a 24-hour period while asleep, awake or recovering from a night of sleep deprivation, help bolster a theory that an important function of sleep is to save energy (SN: 10/24/09, p. 16).

To measure how much energy people use during sleep in a more rigorous way than has been done before, Kenneth Wright, a physiologist at the University of Colorado, and his colleagues studied seven people. Each of the healthy young volunteers lived inside a sealed room for three days. The volunteers were on bed rest the entire time and ate the same amount of calories at the same time each day. The researchers continually monitored the subject's brain waves and how much oxygen and carbon dioxide the person breathed in and out. From there, the team could calculate each person's energy use during each stage of sleep and waking.

"This is a Herculean effort," neurobiologist Paul Shaw of Washington University in St. Louis says of the study. "This will be the gold standard going forward.""

Read more at Wired (Thanks @XxLadyClaireXx)