The fundamental biological importance of sleep is demonstrated by the fact that sleep is observed widely across the animal kingdom, and that sleep deprivation can be harmful both physiologically and cognitively. Likewise, the importance of wake is axiomatic: reproduction, feeding, and escape from predation depend on an animal being awake. However, until recently, the neural circuits that regulate wake and sleep have remained poorly understood. One strand of inquiry has implicated a non-neuronal cell type in sleep-wake control. This cell?the astrocyte?makes up the largest class of non-neuronal cells in the brain, and it has been shown to affect the activity of surrounding neurons. However, the ways in which astrocytes are involved in sleep and wake are largely unexplored. This project tests whether astrocytes sense wake-specific signals and respond to these signals by changing the state of the brain. To perform these experiments, advanced imaging tools to watch different forms of cellular activity in the brain are used. The broader impacts of this project aim to make interdisciplinary research accessible and routine to trainees early in their careers. The motivation for this lies in the fact that trainees with experience in physical sciences are more likely to become tool builders themselves, and that watching science happening in real time can excite and empower trainees to think deeply about the biology around them.