A link between obesity and sleep loss may lie in studying worm metabolism

Can staying up late make you fat? A growing body of research has suggested that poor sleep quality is linked to an increased risk of obesity by deregulating appetite, which in turn leads to more calorie consumption. 

Microscopic image of C. elegans.
Caenorhabditis elegans (C. elegans), seen here under a microscope. (Image: University of Nevada, Reno)

But a new study published in PLOS Biology found that the direction of this reaction might actually be flipped: It’s not the sleep loss that leads to obesity, but rather that excess weight can cause poor sleep, according to researchers from the Perelman School of Medicine and the University of Nevada, Reno, who discovered their findings in the microscopic worm Caenorhabditis elegans (C. elegans).

“We think that sleep is a function of the body trying to conserve energy in a setting where energetic levels are going down. Our findings suggest that if you were to fast for a day, we would predict you might get sleepy because your energetic stores would be depleted,” says study co-author David Raizen, an associate professor of neurology and member of the Chronobiology and Sleep Institute at Penn. 

Raizen emphasizes that while these findings in worms may not translate directly to humans, C. elegans offer a surprisingly good model for studying mammalian slumber. Like all other animals that have nervous systems, they need sleep. But unlike humans, who have complex neural circuitry and are difficult to study, a C. elegans has only 302 neurons—one of which scientists know for certain is a sleep regulator.

This story is by Lauren Ingeno. Read more at Penn Medicine News.