Circadian rhythms are one of the most fundamental processes in nature. Organisms ranging from cyanobacteria to plants and animals exhibit physiological or behavioral changes that are set by the circadian cycle. The fruit fly, Drosophila melanogaster, senses day/night cycles in part through rhodopsin-dependent light reception in their eyes. However, another significant pathway for light entrainment is mediated in central pacemaker neurons. The Drosophila circadian clock is extremely light sensitive. However, the only known light sensor in pacemaker neurons was the flavoprotein, Cryptochrome (Cry), which responds only to high levels of light in vitro. We identified a previously uncharacterized rhodopsin, Rh7, which functions in circadian light entrainment through circadian pacemaker neurons in the central brain. The demonstration that Rh7 functions in circadian pacemaker neurons represents the first role for a rhodopsin in the central brain. Our lab also use flies to study sleep, and we recently revealed mechanisms the timing of sleep.