Sleep could play an important role in mitigating damage to DNA. A new study on zebrafish found that DNA repair in neurons increases during sleep time whereas sleep deprivation prevents genetic restoration.

Imaging of chromosome dynamics (green) in single neuron (red, dashed box) in live larva. Credit: David Zada.

The zebrafish (Danio rerio) has become one of the most popular model organisms in labs around the world. The small tropical fish quickly proved to be extremely useful to researchers when the first big genetic screening projects rolled out in the 1990s. It is thanks to the zebrafish that we now know about hundreds of essential human developmental genes, with a myriad of studies cementing the zebrafish’s predictive model for human development and disease.

Another reason why zebrafish are so popular in research labs is the optical transparency of embryos, making them ideally suited for microscopic imaging of biological processes. For their study, Lior Appelbaum of Bar-Ilan University and colleagues genetically modified zebrafish to have fluorescent chromosomes in their neurons, which allowed them to monitor the movements of these chromosomes while the fish were awake and asleep.

Researchers then found that when the zebrafish were awake, chromosomes tended to be static and sometimes accumulated double-strand breaks — but during slumber, the chromosomes would dissipate some of this DNA damage. 

Subsequent experiments showed that when researchers sleep deprived the fish by tapping on their tanks, double-strand breaks started to form. However, when the fish were given a drug that induced sleep, brain cells showed signs of DNA repair.

“We’ve found a causal link between sleep, chromosome dynamics, neuronal activity, and DNA damage and repair with direct physiological relevance to the entire organism,” Appelbaum said. “Sleep gives an opportunity to reduce DNA damage accumulated in the brain during wakefulness.”

“It’s like potholes in the road,” he added a statement. “Roads accumulate wear and tear, especially during daytime rush hours, and it is most convenient and efficient to fix them at night, when there is light traffic.”

Applebaum and colleagues claim that the organisms must pay a “price of wakefulness” in the form of the accumulation of DNA damage. Sleep may consolidate and synchronize nuclear maintenance within individual neurons. In the future, the authors plan to test this hypothesis.

Previously, researchers at Hong Kong University found a link between sleep deprivation and DNA damage in doctors. Taken together with the present findings, these results suggest that our lifestyle choices can have important ramifications, all the way to our genes.  According to recent research, as many as one-third of all Americans sleep less than six hours a night.

The findings were reported in the journal Nature Communications.