Bacterial Signals Found Within the Brain May Play a Role in Sleep Regulation
Recent research suggests a surprising connection between bacteria and sleep, challenging traditional understandings of how sleep is regulated. Scientists are investigating the possibility that bacterial signals, specifically those from peptidoglycan (PG), a component of bacterial cell walls, actively influence sleep processes within the brain. This work proposes a shift from a solely brain-centric view of sleep to one that acknowledges the crucial role of the body’s microbiome.
For years, PG was known to induce sleep in animal models when directly injected. However, it was generally believed that PG couldn’t naturally access the brain. New findings from researchers, published in Frontiers in Neuroscience, demonstrate the presence of PG, alongside its associated receptor molecules, in various brain regions. Importantly, levels of these components fluctuate throughout the day and are altered by sleep deprivation.
This revelation supports a broader hypothesis, detailed in a recent Sleep Medicine Reviews paper, termed the “holobiont condition” of sleep. This hypothesis integrates two existing perspectives: the traditional view of sleep as a brain-regulated neurological process,and the concept of ”local sleep,” where sleep-like states emerge within small cellular networks throughout the body – a phenomenon observed in “sleep in a dish” experiments.
The holobiont condition proposes that sleep isn’t solely dictated by the brain, nor is it simply an accumulation of cellular inactivity. Instead, it’s a coordinated process resulting from the interaction between the host organism and its resident microorganisms. ”It’s not one or the other, it’s both. They have to work together,” explains researcher [Researcher’s Name – not provided in text]. “Sleep really is a process…because of extensive coordination.”
This research builds on existing knowledge linking the microbiome to sleep, including the impact of sleep patterns on gut bacteria and the increased sleep observed during bacterial infections. The findings suggest a “bottom-up” influence on cognition and behaviour, where the needs and evolutionary history of microorganisms – which predate mammals by billions of years – may shape the activities of their hosts.
Researchers beleive the fundamental mechanisms driving sleep may have originated with the activity cycles of bacteria themselves, and that the molecules involved in these ancient cycles are related to those governing cognition today. Further research will focus on understanding the dialog pathways between humans and their microbial communities, and how these interactions contribute to overall health and sleep regulation.
(source: Washington State University)
