The metabolic cost of an adult missing one night of sleep is the equivalent of walking slightly less than two miles, a new study by a University of Colorado team has found.
"We found that people do expend more energy when they are awake in bed than when they are asleep," said Professor Kenneth Wright.
"While the amount of energy savings for humans during sleep may seem relatively small, it actually was a little more than we expected," said Wright.
The study showed that compared to a typical night of sleep, the amount of energy expended by study subjects during 24 hours of sleep deprivation was up about 7 percent.
In contrast, energy expenditure decreased by about 5 percent during the recovery episode, which included 16 hours of wakefulness following the sleep deprivation night, then eight hours of recovery sleep, Wright said.
The study may have implications for those with sleep disorders such as insomnia or sleep apnea.
"One question we have is why humans don't conserve more energy during sleep. We think there are multiple functions of sleep, and that some energy conserved during sleep may be redistributed to support other important physiological processes," Wright said.
He said more research is needed to understand how short nighttime sleep schedules, typically six hours or less a night across many days, contribute to weight gain and obesity.
The study was published in the January issue of the Journal of Physiology.