In a captivating blend of physics and biology, researchers from Washington University in St. Louis have proposed a new theory on the purpose of sleep, as detailed in their recent publication in Nature Neuroscience.
This study, led by biologist Keith Hengen and his team, delves into the intricate workings of the brain and sleep’s crucial role in maintaining its optimal function.
The team, including physicist Ralf Wessel and graduate students Yifan Xu and Aidan Schneider, embarked on a journey to decipher sleep’s true significance. For long, sleep was seen as a mere antidote to tiredness, a basic necessity without a clear understanding of its deeper role.
Hengen’s team, however, likens the brain to a biological computer that requires sleep to reset and maintain its peak operating condition, a concept they refer to as “criticality.”
Criticality is a state of balance between order and chaos. It’s a concept well-known in physics, but only recently applied to neurobiology.
Wessel explains that in physics, criticality describes systems teetering on the brink between predictable order and unpredictable chaos. In the brain, achieving criticality means optimizing how information is processed and stored.
The team’s innovative research monitored the brain activity of sleeping rats. They discovered that during sleep, the brain resets itself to this critical state.
This finding challenges the traditional view that sleep is for replenishing unknown chemicals drained during wakefulness. Instead, sleep appears to be a systemic solution to a systemic problem – it helps the brain maintain its most efficient state.
In their experiments, the researchers tracked “neural avalanches” – cascades of brain activity in the rats. These avalanches are indicators of how information flows through the brain.
They found that just after the rats woke up from restorative sleep, avalanches of all sizes occurred, signifying a state of criticality.
As the rats stayed awake longer, these cascades began to skew towards smaller sizes, hinting that the brain was moving away from its optimal state. This shift predicted when the rats would need to sleep again to reset.
The idea of criticality was first explored in the late 1980s with physicists studying sand piles on a grid, where they observed spontaneous cascades of varying sizes – a phenomenon surprisingly similar to the neural avalanches observed in the brain.
Each neuron, like a grain of sand, follows simple rules but collectively achieves a complex, critical state.
This study represents a significant interdisciplinary effort. Hengen, Xu, and Schneider conducted the experiments and collected the data, while Wessel applied the mathematical principles of criticality.
Their collaboration bridges the gap between physics and biology, offering a novel understanding of why sleep is vital for our brains. It suggests that sleep is essential for the brain to function at its best, balancing the fine line between order and chaos.
If you care about sleep, please read studies about herb that could help you sleep well at night, and these drugs could lower severity of sleep apnea by one third.
For more information about sleep, please see recent studies that coffee boosts your physical activity, cuts sleep, affects heartbeat, and results showing how to deal with “COVID-somnia” and sleep well at night.
The research findings can be found in Nature Neuroscience.
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