A new study has uncovered the first direct evidence explaining why we sleep, shedding light on the purpose and function of this fundamental human need. Researchers from the University of Washington in St. Louis combined physics and biology to unlock the secrets of sleep, viewing the brain as a biological computer that requires a reset to optimize thinking and processing.
The study draws comparisons between the brain and a complex computer system, highlighting their shared characteristics such as electrical signals and storage capacity. Applying the concept of criticality from the field of physics, which describes a system at the tipping point between order and chaos, the researchers theorized that the brain operates similarly. They suggest that the brain constantly shifts away from this critical state during wakefulness, prompting the need for sleep to restore optimal functioning.
The research team previously explored the criticality theory in 2019, demonstrating that the brain actively maintains criticality. In this latest study, they focused on understanding the role of sleep in relation to criticality. By observing the electrophysiological responses of single neurons in the visual cortices of young rats throughout their sleep/wake cycles, they found that sleep restored criticality in the brain.
The researchers closely monitored neural avalanches, which are cascades of brain activity, and noticed a pattern. When the rats had just woken up from restorative sleep, avalanches of all sizes were observed. However, during periods of wakefulness, the cascades shifted towards smaller and smaller sizes. By tracking the distribution of neural avalanches, the researchers could predict when the rats were about to sleep or wake up.
These results suggest that every waking moment pushes the brain away from criticality, and sleep helps the brain reset, explained Keith Hengen, corresponding author of the study.
Overall, the data support a model where sleep functions to restore criticality, which is progressively undermined during wakefulness. The researchers propose that maintaining criticality is the core regenerative function of sleep.
The findings of this study offer valuable insight into the purpose of sleep, a question that has puzzled scientists and researchers for generations. While various hypotheses exist, such as sleep’s role in toxin removal, memory consolidation, and cellular repair, this study presents the first direct evidence to support a comprehensive explanation.
Understanding why we sleep is not only of scientific interest but also holds significant implications for human health and well-being. Sleep disorders and chronic sleep deprivation have been linked to a wide range of health issues, including cognitive decline, mood disorders, and increased risk of chronic diseases.
Although this study was conducted on rats, the researchers believe that the principles of criticality and sleep restoration apply to humans as well. Further research will be necessary to validate these findings and explore potential applications for improving sleep quality and overall brain function.
As we await further discoveries and advancements in sleep science, one thing remains clear: sleep plays a vital role in maintaining our brain’s optimal functioning and should be prioritized for our well-being and cognitive abilities.
