Sleep Regulated by Gut Bacteria: Bacterial Molecules Found in Brain Reset Sleep Science

Groundbreaking Discovery: Gut Bacteria Send Sleep-Regulating Molecules to the Brain

SEATTLE, WA – September 25, 2025 – A landmark study from Washington State University (WSU) is fundamentally rewriting the textbook explanation of sleep. Researchers have confirmed that molecules produced by our gut bacteria journey to the brain, where they directly influence the sleep-wake cycle. This discovery of a direct "gut-brain sleep axis" positions the microbiome as a master regulator of sleep, challenging decades of brain-centric dogma.

For lead author Erika English, a PhD candidate at WSU, the findings provide a missing piece to the puzzle of sleep. "We found that peptidoglycan, a building block of bacterial cell walls, is naturally present in the brain at levels that rise and fall with our sleep patterns," English explained. "This adds a new dimension to what we already know."

The study validates the revolutionary "holobiont hypothesis" of sleep, which proposes that sleep emerges from a partnership between the human body and its trillions of microbial inhabitants. "It's not one or the other, it's both. They have to work together," English said, describing sleep as a coordinated process across multiple levels of biology.

The implications are profound, tracing the evolutionary roots of sleep back billions of years. "We think sleep evolution began eons ago with the activity/inactivity cycle of bacteria," said co-author Professor James Krueger, a renowned sleep scientist. The molecules that governed primordial bacterial rhythms may now be directing human cognition and sleep.

This paradigm shift points toward a future where sleep disorders could be treated by targeting the gut microbiome. Instead of focusing solely on brain chemistry, therapies might involve probiotics or dietary interventions designed to optimize the bacterial signals that promote natural sleep.

As English concludes, "It's a very exciting time to expand on our understanding of how we are communicating with our microbes." This research not only deepens our understanding of a fundamental human experience but also illuminates a promising new path toward achieving restorative sleep.