A high-protein diet may promote deep sleep, according to a study that found mice and flies that ate more protein were less likely to wake up from movement-related disturbances.
When you go to sleep you stop consciously observing the world, including things that can disrupt sleep, say Dragna Rogulja at Harvard University. “We wanted to understand how it is that you can suppress sensory stimuli.”
She and her colleagues assessed how 3,400 genes affect sleep in fruit flies. Working with groups of eight flies, they isolated each of these genes, for a total of 27,200 gene-edited flies. The researchers monitored the flies as they slept on platforms above loudspeakers, which produced intermittent vibrations.
Low-frequency vibrations woke up about 85 percent of flies in which one of two genes was silenced: the first controls the production of a chemical messenger called CCHa1, which regulates circadian behavior, and the second controls CCHa1’s receptor. Both genes are expressed in the nervous system and the intestine.
Removing these genes from the gut alone was sufficient to make the worms more likely to wake up during vibration. Further analysis found that certain cells in the gut produce CCHa1 when exposed to the protein. CCHa1 then travels from the gut to the brain where it suppresses arousal during sleep.
Taken together, these findings suggest that the protein plays a role in inhibiting arousal during sleep. To confirm this, the team fed flies either a high-protein diet or a regular diet for a day. Half of the flies on the high-protein diet woke up in response to the vibration as much as the flies on the regular diet. A similar experiment in rats produced comparable results.
“The general idea makes sense. We sleep when our other needs are met,” says rafael pelayo at Stanford University in California. “So, if you have some better quality food, in the sense a protein-rich diet, it will help you sleep soundly. At least it did in flies and mice. This may not apply to humans.
The findings also apply to mechanical stimuli such as mere shaking. The genetic changes didn’t change how readily the animals wake to other disturbances, such as heat or sound, says Rogulja, which means that many other pathways also control arousal during sleep.