Previous studies that have looked at the connection between sleep and metabolism have determined that blood sugar goes up after a night of poor sleep because the body's muscles become less sensitive to the hormone insulin. Insulin resistance leads to myriad problems in the body, including diabetes, polycystic ovary syndrome, heart disease, and cancer.
The new study found that insulin resistance isn't the only problem caused by short sleep, however.
Too little sleep appears to prevent the pancreas from making enough insulin to meet the body's energy demands.
"The pancreas is tired," Buxton says, and isn't "responding adequately."
Why that happens, he says, is still a mystery.
"There's plenty of insulin packaged and ready to go. Somehow it's either not sensing the actual glucose level, or not responding with an adequate or typical response," he tells WebMD.
The good news is that the metabolic disruptions reversed after people in the study were once again allowed to get plenty of sleep on a regular schedule.
The study is some of the strongest evidence to date that short and disrupted sleep is bad for the body's metabolism.
Other studies, which have been shorter or based on more indirect evidence, have shown, for example, that children and adults who sleep less than about six hours a night are more likely to be overweight and have diabetes than people who sleep more than that.
"It's not that it's new information. It's that it provides a lot more information about the combined and potential long-term health effects" of sleep disruption and deprivation, says Charles Bae, MD, a neurologist at Cleveland Clinic in Ohio.
Bae is an expert on sleep disorders, but he was not involved in the research.
Advice for the Tired and Overworked: Don't Sacrifice Sleep
"What I tell my patients is to make sleep a priority," Bae says. "For everybody -- and I'm at fault, too -- sleep is the easiest, quickest thing to either get rid of or cut into because we're all so busy."
"On top of that, if you have to work at different hours, and in this economy you take what you can get, that also means you're less likely to get sleep during the day. Especially if you have demands on your time from family and friends," Bae says.