Whenever you are injured, a type of skin cell known as fibroblasts, move into the region to pave the way for new cells to grow. Fibroblasts are known to “keep their own time,” writes Roni Dengler at Science, periodically changing activity depending on the time of day. But the details of the process remained largely unclear.

To better understand these rhythms, Nathaniel Hoyle and his team at the Laboratory of Molecular Biology in Cambridge took a closer look at the fibroblasts. While studying how proteins produced by the cells vary throughout the day, they discovered that proteins important to healing were most abundant when the sun was up.