Scientists at Johns Hopkins University in Maryland have discovered a newly discovered brain circuit in mice. This finding may help to account why these animals have a longer and deeper rebound sleep following periods of sleep loss. Under the leadership of Mark Wu, the team uncovered intricate brain circuits at play in sleep, zooming in on 11 as-yet-unknown regions of interest.
To better understand the mechanism, the scientists injected a fluorescent tracer into 11 specific brain areas that were already known to induce sleep. This sleep tracer uncovered 22 interrelated states related to at least four sleep-promoting spaces. These discoveries represent a giant leap in our ability to identify underlying biological mechanisms of sleepiness. Moreover, they shed light on how restorative sleep is generated following sleep loss.
William Giardino, who studies at Stanford University in California and is a colleague of Hansman’s, raised a crucial caveat. Whether analogous circuits are present in humans remains an open question. The long-term effects of this study are very hopeful, opening doors to new treatments for people suffering from throngs of sleep disorders.
The study observed that deactivating the thalamic nucleus reuniens—the brain cells responsible for a key sleep-inducing function—resulted in less sleepy behavior among sleep-deprived mice. Interestingly, these altered mice were more hyperactive and spent less time building nests than controls. Instead, on average, the sleep-deprived mice got 10 percent less non-REM sleep.
Each mouse was assigned to one of 11 groups, grouped in threes or fours. In a third series of studies, the researchers selectively stimulated specific regions within these categories. It would normally take the mice a few hours to fall asleep after being stimulated. At that time, they exhibited behaviors that suggested they were preparing to sleep.
On an average day, when you prepare for bed, you may brush your teeth, wash your face. Next you shake out your pillow or smooth your bedding and fall asleep to Sweet dreams. retorted Mark Wu. Needless to say, he described the odd behavioral patterns that were resulting from these shifts in the mice. They polish their noses, stroke their whiskers, and fringe their nests,” he wrote.
This study improves our understanding of the neural mechanisms of sleep in mice. Additionally, it lays the groundwork for future breakthroughs in sleep disorder treatment with human applications. Researchers are revealing the intricate processes involved in the brain’s operation while we’re sleeping. We look forward to this research translating into practical, easy-to-implement interventions to help the millions of Americans who aren’t getting the sleep they need.
