The latest research reveals that the complex microbial community in our digestive system is not just an aid to digestion, but a "chemical engineer" that makes hormones and regulates the signals that determine our ability to sleep and wake up.
After decades of focusing exclusively on brain activity, the gut-brain axis is now emerging as a key player in the sleep equation, acting as a vital bridge through which biochemical messages travel, directly influencing melatonin production, hormone balance, and even our response to stress and anxiety. This constant communication means that any change in gut health is immediately translated into signals that affect how the brain manages stress and mood, and therefore, our readiness for sleep.
This discovery not only explains why people with irritable bowel syndrome and sensitive intestines suffer from sleep disorders, but also opens the door to new treatments aimed at improving sleep by taking care of the digestive system.
But how exactly do the gut communicate with the brain?
The beneficial microbes in our gut do more than just aid digestion; they are living chemical factories. These microbes produce neurotransmitters and chemicals that directly affect sleep. For example, most of the body's serotonin (about 90%) is produced in the gut. This hormone regulates mood and is a pathway for the production of melatonin, the sleep hormone, which is also partially made in the digestive tract. Beneficial gut bacteria also produce GABA, a neurotransmitter that calms the nervous system and signals that the body is in a safe state, allowing it to relax.
Together, these substances form a system that supports the body's natural circadian rhythm. But when the microbiome becomes unbalanced and harmful bacteria proliferate, this chemical production is disrupted, and the "time to sleep" signals become unclear or weak.
In addition, another key pathway linking gut health to poor sleep is chronic, low-grade inflammation. A healthy gut maintains a strong barrier that prevents toxins and inflammatory molecules from leaking into the bloodstream. When this barrier is compromised, as in cases of "leaky gut" or irritable bowel syndrome, it weakens, allowing substances that trigger the immune system to leak out. This leakage leads to persistent inflammation throughout the body.
Inflammation, as is well known, disrupts areas of the brain responsible for regulating sleep-wake cycles, making it difficult to transition smoothly between sleep stages. Inflammation also raises levels of the stress hormone cortisol, putting the body in a constant state of alert that interferes with the relaxation necessary for sleep.
And so a vicious cycle ensues: stress harms the diversity of the gut microbiome, a disturbed gut sends inflammatory and anxiety signals to the brain, disrupting sleep, and poor sleep in turn increases stress hormones, making the situation worse in the gut.
The good news is that this cycle can be broken by supporting gut health, which has a noticeable and positive impact on sleep quality. This doesn't require complicated solutions; practical measures such as:
Eat foods rich in probiotics (such as fermented dairy products and natural pickles) and prebiotics (such as bananas, oats, and asparagus) to feed the beneficial bacteria.
Reduce sugar and ultra-processed foods that feed harmful bacteria and increase inflammation.
Adhering to regular meal times helps regulate the biological clock of the digestive system.
Managing stress through breathing techniques or meditation, to protect the microbiome from its negative effects.
Drink sufficient amounts of water to support a healthy gut environment.
Experts point out that good sleep doesn't begin the moment you get into bed, but long before, and is shaped by gut health and the signals it sends to the brain throughout the day. When the gut is supported and balanced, the body becomes more capable of calming down, recovering, and shifting into rhythms that allow sleep to improve naturally.
