Researchers have discovered that small regions of the brain can take brief, millisecond-long “micro-naps” while the rest of the brain remains awake. This finding challenges the traditional understanding of sleep and wakefulness based on slow, long-lasting brain waves. The study, a collaboration between the University of California Santa Cruz and Washington University in St.
Louis, analyzed vast amounts of brain wave data from mice using an artificial neural network. The researchers found that sleep can be detected by patterns of neuronal activity just milliseconds long, 1000 times shorter than a second. With powerful tools and new computational methods, there’s so much to be gained by challenging our most basic assumptions and revisiting the question of ‘what is a state?'” said Keith Hengen, Assistant Professor of Biology at Washington University.
“Sleep or wake is the single greatest determinant of your behavior, and then everything else falls out from there. So if we don’t understand what sleep and wake actually are, it seems like we’ve missed the boat.”
The researchers also observed that individual brain regions can briefly transition between sleep and wake independently, revealing complex, localized brain activities.
Micro-naps in brain regions
These “flickers” suggest that small brain regions might momentarily switch between sleep and wake states. David Haussler, Distinguished Professor of Biomolecular Engineering at UC Santa Cruz, noted, “We’re seeing information at an unprecedented level of detail. The previous feeling was that all relevant information was in the slower frequency waves.
This paper says, if you look at the details of the high-frequency measurement over just a thousandth of a second, there is enough there to tell if the tissue is asleep or not. This tells us that something very fast is going on — that’s a new hint to what might be happening in sleep.”
The research, carried out by Ph.D. students David Parks (UCSC) and Aidan Schneider (WashU), suggests that hyper-fast patterns of activity between just a few neurons are fundamental elements of sleep. Traditional slow waves may act to coordinate these fast, local patterns of activity, but the fast patterns appear closer to the true essence of sleep.
The findings open new avenues for understanding localized brain functions and their implications for neurological health. The researchers believe that their method of measuring sleep-wake states could uncover new secrets about how we slumber and encourage more investigations into these “flickers.
“This gives us potentially a very, very sharp scalpel with which to cut into these questions of diseases and disorders,” Hengen said. The more we understand fundamentally about what sleep and wake are, the more we can address pertinent clinical and disease-related problems.”
The study was published in the journal Nature Neuroscience and could significantly impact our understanding of neurological diseases related to sleep dysregulation.
