Lack of sleep and sleep disturbances have been linked to decreased cognitive performance, premature aging and other brain disorders — and scientists are just discovering why.

According to research published in the journal Nature Communications, every day your DNA is damaged by things like radiation and oxidative stress, and this damage accumulates faster than your body can repair it during daylight hours. It’s only during sleep, when your brain is offline so to speak, that your body can effectively normalize and repair your DNA.

Study authors compare this process to roadwork: Potholes occur because of wear and tear on the roads. During daytime and rush hour, repairing those holes is not effective or efficient, but it is easier and more effective to repair them at night when traffic is light.

Bottom line: Get at least seven to nine hours of uninterrupted sleep per night for top-notch chromosomes.