I read an interesting article published in Nature Communications that described how zebrafish larvae need sleep to help fix damaged DNA that accumulates in their brains during the day. The researchers engineered zebrafish larvae to have fluorescent chromosomes in a single neuron, which allowed them to observe double-strand breaks in the DNA build-up during wakefulness. In contrast, chromosome activity necessary for repair increased when the animals were sleeping. If the researchers disrupted the animal’s sleep, there were more breaks in the DNA. On the other hand, promoting sleep by adding a sleeping aid to the water helped increase chromosome activity.
This research suggests that sleep is important for repairing neuronal DNA whereas this repair process is less effective during wakefulness when the brain is active. The researchers speculate that sleep may have evolved to give the brain a way to repair damage that has accumulated during the day.
Zada D, Bronshtein I, Lerer-Goldshtein T, Garini Y, Appelbaum L. Sleep increases chromosome dynamics to enable reduction of accumulating DNA damage in single neurons. Nature Communications. 10: 895, 2019.