The Lewis lab will explore the complex neural circuits that guide us through sleep. In recent years, neuroscientists have identified multiple structures—small clusters of neurons deep within the brain—that serve as switches between sleep and wakefulness. But why do so many switches exist, and do they also regulate the different stages within the sleep cycle, from deep sleep to dreaming? In my laboratory, we use a sophisticated suite of imaging techniques that allows us to simultaneously monitor the activity of dozens of these tiny, hard-to-observe structures in people as they sleep. Now, combining this approach with sophisticated behavioral, statistical, and computational analyses, we will determine how these structures interact as volunteers transition through distinct stages of sleep, and assess whether distinct patterns of activity are linked to dreaming, waking, or an awareness of sensory information—such as sounds that are heard while asleep. Our work could provide a deeper understanding of how sleep promotes healthy brain function and why it is disrupted in neurological and psychiatric disorders.