Sleep is vital in both protecting against and healing from sickness, according to new findings in fruit flies.
The research, in the form of two new studies, is published in the journal SLEEP and was conducted by researchers from the Perelman School of Medicine at the University of Pennsylvania.
In the first study, researchers demonstrated that increased sleep after infection with bacteria is associated with greater survival. For the study, they purposely infected fruit flies that were either sleep-deprived or non-sleep-deprived with Serratia marcescens or Pseudomonas aeruginosa bacteria.
Researchers found that that flies that were sleep-deprived actually had greater survival after the infection, compared with the non-sleep-deprived flies. Sleep deprivation seemed to make the fruit flies sleep more after being infected with the bacteria.
"We deprived flies of sleep after infection with the idea that if we blocked this sleep, things would get worse in terms of survival," study researcher Julie A. Williams, Ph.D., a research associate at the university's Center for Sleep and Circadian Neurobiology, said in a statement. "Instead they got better, but not until after they had experienced more sleep."
Researchers also examined the role of a transcription factor called Relish that is necessary to fight infection. They found that when they genetically engineered fruit flies to lack Relish and another kind of transcription factor, depriving these flies of sleep before exposing them to the infection didn't make them sleep for longer after being infected -- and the potential survival benefit of sleep deprivation in increasing sleep post-infection was erased.
In the second study, researchers genetically engineered flies to sleep more before they were infected with bacteria. These flies survived longer after infection, and were also better able to clear the bacteria from their bodies -- suggesting sleep has a positive effect on the immune response.
"Increasing sleep enhanced activity of NFkB transcription factor, increased resistance to infection, and strongly promoted survival. Together, these findings support the hypothesis that sleep is beneficial to the host by maintaining a robust immune system," the researchers wrote in the study.