Sleep is among the most enduring mysteries in biology. We spend a third of our lives asleep, sleep disorders are common, and sleep is evolutionarily conserved, yet mechanisms that underlie this behavioral state remain poorly understood. We are taking a new approach to this problem by exploiting useful features of zebrafish to answer a basic question: What genetic and neuronal mechanisms underlie sleep? We are addressing this question using a combination of genetics, behavioral assays, optogenetic and chemogenetic perturbations, whole-brain imaging, and electrophysiology, which together are providing new insights into mechanisms that underlie sleep and wakefulness.