FRIDAY, Aug. 24, 2018 (HealthDay News) -- One sleepless night might tip the body's metabolism toward storing fat while depleting muscle, new research suggests.

Many studies have linked poor sleep -- whether from insomnia or working the night shift -- to weight gain and health conditions like type 2 diabetes. But that type of research leaves open the question of whether sleep loss itself is to blame.

A growing number of lab studies, zeroing in on the effects of sleep deprivation, suggest the answer is "yes." The new research adds to the evidence.

"We need mechanistic studies to understand the effects of sleep loss," said lead researcher Dr. Jonathan Cedernaes, a research associate at Northwestern University, in Chicago.

Cedernaes said studies have shown, for example, that sleep loss can change a range of markers in the blood -- including blood sugar, hormone levels and various byproducts of metabolism.

For the new study, his team dug into the effects within fat and muscle tissue -- looking at how gene activity and protein levels in those tissues changed after a sleepless night.

The investigators found that in 15 young, healthy men, one night of sleep loss triggered changes that favored fat storage and muscle breakdown.

"This doesn't mean you should be alarmed by one night of sleep loss," Cedernaes stressed. But, he added, the study raises the question of what would happen if poor sleep becomes a regular pattern.

The findings were published online Aug. 22 in the journal Science Advances.

A sleep researcher who was not involved in the study called the findings "extremely important."

"The finding that skeletal muscle proteins decrease, and [fat-promoting] proteins increase, in response to sleep loss is a novel mechanism by which sleep loss may promote obesity and weight gain," said Josiane Broussard, an assistant professor at Colorado State University, in Fort Collins.

With any lab study, however, it's not clear how well the artificial conditions reflect real life.

Dr. Eva Szentirmai, an associate professor at Washington State University, in Spokane, who studies sleep and metabolism, said, "We don't know if you would observe similar tissue-specific changes during long-term, habitual sleep loss -- which is common in our society."