Gut microbes regulate stress via the circadian clock
How gut microbes might help manage stress and keep your internal clock ticking…
Think of your body as a well-orchestrated symphony, with every organ, tissue and cell harmonising to maintain your daily rhythms. Behind the scenes, a hidden team of helpers – your gut microbes – plays a starring role in regulating this performance, especially your stress response and internal clock.
Recent research highlights how much our gut microbiota (the trillions of microorganisms living in our digestive system) influence our circadian rhythms – our body's natural ‘internal clock’ that governs sleep-wake cycles, hormone release, and other daily patterns. Here's what scientists discovered and why it matters.
Gut microbe activity aligns with the circadian rhythm.
Gut Microbes and the Stress Hormone Symphony
The researchers focused on corticosterone, a stress hormone in rodents (similar to cortisol in humans). This hormone naturally fluctuates throughout the day, peaking and dipping in a predictable rhythm. Gut microbes, it turns out, are instrumental in keeping these cycles running smoothly.
When gut microbes are absent, such as in germ-free mice, these daily cycles go haywire. Stress hormone peaks become irregular, especially during sleep-wake transitions. This disruption throws the brain off rhythm, with consequences for stress management and emotional regulation.
Key Brain Players in Stress and Circadian Regulation
Several brain regions work together to manage stress and maintain daily rhythms:
Suprachiasmatic Nucleus (SCN): Known as the body's ‘master clock’, the SCN is the primary regulator of circadian rhythms.
Hippocampus: Essential for memory and learning, the hippocampus also plays a role in managing stress responses.
Amygdala: The amygdala processes emotions, particularly fear and stress.
Without gut microbes, these brain regions lose their usual patterns of gene activity. This disruption alters how the body responds to stress and keeps time.
The Gut-Brain Connection: Rhythms in Sync
The study revealed that gut microbes influence diurnal rhythms, the day-night cycles of stress hormones. Removing gut microbes not only disrupted these rhythms but also led to time-specific changes in stress responses. For instance:
Germ-free mice had reduced stress hormone release at certain times of the day.
Their social behaviours were altered, showing time-sensitive impairments.
A Star Player: Lactobacillus reuteri
One gut bacterium, Lactobacillus reuteri, stood out for its role in regulating stress hormone levels depending on the time of day. Transplanting gut microbes from one mouse to another confirmed that gut microbial rhythms shape the cycles of stress hormones.
Modern Life and Gut Disruption
The research underscores how gut microbes synchronise with our circadian clock to manage stress. However, disruptions in this delicate balance, caused by chronic stress, poor diet, lack of sleep or inflammation, can throw the system off, contributing to stress-related disorders and irregular hormone cycles.
Why Did This Evolve?
We can speculate that this gut-brain partnership evolved as a mutual benefit for both the host (us) and the microbial community. By aligning their rhythms, both parties maximise survival, efficiency and adaptability, forming a cooperative unit known as the ‘holobiont’, a partnership of host and microbes.
What Does This Mean for You?
This research highlights how closely our gut health is tied to stress management and overall wellbeing. Supporting your gut microbiome, through exposure to nature, a diverse diet rich in fibre and fermented foods, managing stress, and getting enough sleep, may help maintain your body's natural rhythms and improve your resilience to stress.
polyphenol-rich foods are great for the gut microbiome.
Your gut microbes are active players in your health. By caring for them, you’re helping ensure a harmonious performance every day. By looking after your gut microbiome, you’ll likely be happier, healthier and more productive.
Head over to the Nature. Gut. Brain. YouTube channel to learn more: https://www.youtube.com/@naturegutbrain
Find the study here: https://www.cell.com/cell-metabolism/fulltext/S1550-4131(24)00399-1
Check out the book Invisible Friends for more about why microbes are awesome! https://pelagicpublishing.com/products/invisible-friends
