Sleep loss is known to impact key processes such as attention, cognition, learning, memory, metabolism, and immune function.
New research suggests that astrocytes, which are little-studied brain cells, may influence the need for sleep and could eventually help humans go longer without sleep while avoiding negative effects on mental fatigue and physical health.
The findings, published in the Journal of Neuroscience, demonstrated that activating these cells kept mice awake for hours when they would normally be resting, without making them any sleepier. Understanding these cells could help develop medications to improve the productivity, safety, and health of shift workers and others who work long or odd hours, such as first responders and military personnel. Sleep loss and mistimed sleep are known to impact key processes, such as attention, cognition, learning, memory, metabolism, and immune function.
“Extended wakefulness normally increases sleep time and intensity, but what we saw in this study was that despite hours of wakefulness these mice did not differ from well-rested controls in terms of how long and how intensely they slept,” explained senior author Marcos Frank, PhD, a neuroscientist and professor at the Washington State University Elson S. Floyd College of Medicine, in a press release. “This opens up the possibility that we might someday have interventions that could target astrocytes to mitigate the negative consequences of prolonged wakefulness.”
Astrocytes are non-neuronal cells that interact with neurons, which transmit easily measured electrical signals from the brain to other parts of the body. Although astrocytes were previously thought of as merely the “glue” that holds the brain together, new findings have shown that they play an active role in various behaviors and processes through a more subtle and difficult-to-measure process known as calcium signaling. For example, a previous study showed that suppressing astrocyte calcium signaling throughout the brain resulted in mice building up less sleep need after sleep deprivation.
In their new study, investigators looked specifically at astrocytes in the basal forebrain, a brain region known to play a critical role in determining time spent asleep and awake, as well as the amount of sleep needed. Using chemogenetics—a method to control and study signaling pathways—the investigators activated these astrocytes and found that this resulted in mice staying awake for 6 hours or more during their normal sleep period.
Notably, the investigators did not see subsequent changes in sleep time or intensity in response to the added wakefulness, which would normally be expected.
“Our findings suggest that our need for sleep isn’t just a function of prior wake time but is also driven by these long-ignored non-neuronal cells,” said first author Ashley Ingiosi, PhD, an assistant professor of neuroscience at Ohio State University, in the press release. “We can now start to pinpoint how astrocytes interact with neurons to trigger this response and how they drive the expression and regulation of sleep in different parts of the brain.”
In future research, the team plans to conduct behavioral tests in mice to determine how activating basal forebrain astrocytes to induce wakefulness might impact other processes, such as attention, cognition, learning, memory, metabolism, and immune function.
Van Dongen J. Lesser-known brain cells may be key to staying awake without cost to cognition, health. WSU Insider. August 17, 2023. Accessed August 17, 2023. https://news.wsu.edu/press-release/2023/08/17/lesser-known-brain-cells-may-be-key-to-staying-awake-without-cost-to-cognition-health/