Recent studies have highlighted how both obesity and not getting enough sleep can lead to any number of negative health consequences. Now, researchers from the University of Pennsylvania School of Medicine say that one can cause the other.
“Sleep is intricately connected with metabolism,” the researchers said. “Acute disruption of human sleep results in elevated appetite and insulin resistance, and chronically short-sleeping humans are more likely to be obese and diabetic.”
The link between obesity and sleep
The researchers conducted their study on the C. elegans worm to determine the link between obesity and sleep. They began by manipulating the neuron responsible for sleep. They observed that the worms’ energy levels dropped quickly and drastically without sleep. However, they also noticed an increase in fat storage.
“We think that sleep is a function of the body trying to conserve energy in a setting where energetic levels are going down,” said researcher Dr. David Raizen. “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...That suggests that sleep is an attempt to conserve energy; it’s not actually causing the loss of energy.”
In the second part of the experiment, the researchers modified the worms’ genetic expression again. Because a lack of sleep was associated with increased fat, they manipulated the way fat was stored throughout the worms' bodies and allowed them to rest as they typically would. With a more direct expression of where to store the fat, the worms returned to their normal sleeping habits.
Ultimately, the researchers think there is a communication issue between the storage of fat cells and the body’s ability to sleep that can be translated to humans struggling with both sleep and obesity.
“There is a common, overarching sentiment in the sleep field that sleep is all about the brain, or the nerve cells, and our work suggests that this isn’t necessarily true,” said Dr. Raizen. “There is some complex interaction between the brain and the rest of the body that connects to sleep regulation.”