Astrocytic modulation of synaptic transmission in sleep/wake regulation

Lack of sleep is a hallmark of modern society, having negative impacts on health, cognitive function, and the economy. Therefore, it is important to develop effective strategies to promote sleep when necessary. For this goal, we must understand how the brain detects lack of sleep and counters the situation. Theoretical models show that sleep need or pressure builds up while we stay awake, and when it reaches a certain level sleep ensues. However, how this occurs in the brain is still unclear. To address this question, we have turned our attention to brain cells called astrocytes. Astrocytes have long been thought to be "house-keeping" cells that only have supporting roles in the brain; however, recent research has shown that they are important, active players in various brain functions and behaviours. Indeed, our new research revealed that astrocytes control stimulatory signals to neurons that promote wake or sleep. Furthermore, lack of sleep changes how astrocytes control this, and these changes are opposite, or different, for wake-promoting and sleep-promoting neurons. In the proposed research, we will determine the mechanisms by which astrocytes regulate incoming signals to neurons that induce wake or sleep and how this changes when rodents are briefly deprived of sleep. Furthermore, we will investigate how disrupting or mimicking this astrocyte function would affect sleep pressure build-up during sleep loss. The proposed research will help us better understand how the brain monitors sleep need and tries to promote sleep when necessary. Understanding these basic sleep mechanisms is critical for developing effective strategies to reduce the negative impacts of the insufficient sleep that is prevalent in our society.