08/22/2025
🧠 GUT-BRAIN CONNECTION: How Your Gut Influences Mood, Stress & Sleep
Your gut does more than digest food — it also talks directly to your brain. Through the gut-brain axis, your digestive system sends real-time signals to the brain via the vagus nerve. When your gut is inflamed or imbalanced (dysbiosis), it can impact your ability to feel calm, focused, or rested..
1. Serotonin Production Starts in the Gut
🧠 About 95% of serotonin is made in the gut, not the brain.
Produced by specialized gut (enterochromaffin) cells, serotonin supports mood and digestion.
When gut health is compromised—through dysbiosis, inflammation, or leaky gut—serotonin production can drop, leading to:
- Anxiety
- Low mood
- Brain fog
2. Serotonin → Melatonin = Sleep Regulation
Serotonin is also the precursor to melatonin, your sleep hormone.
Melatonin is produced in the brain, but if serotonin production is low, melatonin levels can drop too—leading to:
- Trouble falling asleep
- Light or restless sleep
- “Tired but wired” fatigue
3. The Gut Talks Directly to the Nervous System
The gut is connected to the brain via the vagus nerve—a direct superhighway between your digestive tract and your central nervous system. When your gut is inflamed, irritated, or imbalanced (as in dysbiosis), it can stimulate the body’s stress response through this pathway.
This triggers:
- Increased cortisol levels
- Increased sympathetic (“fight or flight”) activity
- Decreased parasympathetic (“rest and digest”) tone
4. Microbiome & Mental Health
Your gut microbiome—made up of trillions of bacteria, yeast, and other microbes—plays a key role in neurotransmitter regulation. Imbalances in the microbiome (dysbiosis) can:
- Reduce GABA (your brain’s calming neurotransmitter)
- Alter dopamine and serotonin levels
- Increase production of fermentation byproducts and toxins that affect brain function
This can show up as:
- Brain fog
- Anxiety or mood swings
- Feeling overwhelmed for “no reason”
Click the link below to book your next appointment with Dr. James Yoon.
https://bit.ly/4fOCrFT