Tuco-tucos are subterranean rodents that spend most of the day isolated in dark tunnels. Like us, they have a biological clock that indicates the time of day internally to the body. Just like human clocks, the tuco-tucos’ clock need to be adjusted daily to the day and night of the environment by light/dark cycles. How do these animals, that live in underground tunnels, adjust their internal time to the environmental day/night? In this article we show how tuco-tucos synchronize their internal clocks through an integrated field, laboratory and computer simulation work.