Nemuri, the gene that increases the need for sleep has been discovered by researchers from the Perelman School of Medicine at the University of Pennsylvania. These findings are published today in Science.
The NEMURI protein fights germs with its inherent antimicrobial activity and it is secreted by cells in the brain to drive prolonged, deep sleep after an infection.
‘In response to infection, NEMURI appears to kill microbes, most likely in the peripheral parts of the fruit fly body, and increases sleep through its action in the brain. ’
Humans spend nearly one-third of their lives in slumber, yet sleep is still one of biology's most enduring mysteries. Little is known about what genetic or molecular forces drive the need to sleep—until now.
"While it's a common notion that sleep and healing are tightly related, our study directly links sleep to the immune system and provides a potential explanation for how sleep increases during sickness," said senior author Amita Sehgal, PhD, a professor of Neuroscience and director of Penn's Chronobiology Program.
Without the nemuri gene, flies were more easily aroused during daily sleep, and their acute need for an increase in sleep—induced by sleep deprivation or infection—was reduced. On the other hand, sleep deprivation, which increases the need for sleep, and to some extent infection, stimulated nemuri to be expressed in a small set of fly neurons nestled close to a known sleep-promoting structure in the brain.
Overexpression of nemuri increased sleep in bacteria-infected flies and led to their increased survival compared to non-infected control flies.
Several molecules like NEMURI, which is an antimicrobial peptide (AMP), have multiple functions that help combat infection, but its sleep-promoting role may be just as important for host defense, the researchers suggest, given that increased sleep during sickness promotes survival in the flies.