The gastrointestinal microbiome and its effects on human health have been all over the media lately. While we have known for hundreds of years that there are bacteria in our gut, we are just beginning to grasp their diversity and complexity. Some recent studies have focused on the circadian rhythm of these tiny bacteria. Like all living creatures, gut bacteria have internal clocks that govern a variety of important biological processes. Our own actions can knock the gut bacteria circadian rhythm out of sync, with serious consequences to human health.

The Inner Life of Your Gut

Your gastrointestinal tract is lined with billions of bacteria. Although we are not physically aware of these microbes, they affect our health in a variety of ways. In addition to assisting in digestion and the absorption of key nutrients, our gut bacteria help to regulate our immune system and can impact most of our organs.

All organisms have a circadian rhythm. Although our internal clocks are innate, they can be influenced by external cues. For humans, sunlight and temperature both serve as powerful cues. For the gut bacteria circadian rhythm, our own actions make up the majority of the environmental cues. Some bacteria respond to hormones such as melatonin that are released according to our own internal clocks. Others respond to the presence of food in the GI tract.

Our microbiomes are constantly in flux. As we go through the day, the number of different kinds of bacteria can change dramatically. In addition, their location in our gut also can differ based on timing. We have co-evolved to have a symbiosis, in which our gut bacteria help us to maintain good health and vice-versa.

What Happens When Your Gut Bacteria Circadian Rhythm is Out of Sync?

Many humans live dysregulated lives, eating at a wide variety of times and sleeping whenever we get the chance. This affects our bodies in many ways, but also can affect the organisms that live symbiotically with us. This in turn can have further effects on our health. When our microbiome gets off track, the impact can be far-reaching.

Researchers have used a variety of techniques to learn more about the link between our gut bacteria circadian rhythm and our own health. In one experiment, Israeli researchers measured levels of different enzymes in the bloodstream over the course of a day. Liver enzymes, which are crucial for detoxification of the body, vary widely over a standard 24-hour day. When mice were fed at different times of day than they were used to, their microbiome and liver enzymes became more dysregulated. When the microbiome was further disrupted using antibiotics, their liver enzyme production was so dysregulated that the mice were unable to handle high doses of common medications such as Tylenol.

In addition to affecting the function of key organs such as the liver, our gut bacteria appear to impact our own circadian rhythm. A few smaller studies have suggested that our circadian rhythms respond to the chemicals released by gut flora, similar to how they respond to our own melatonin.

The Endless Effects of Circadian Rhythm Disruption

Our own circadian disruption can affect the internal clocks of our gut bacteria, which in turn further disrupts our own circadian rhythm. It is easy to see how this could create a self-perpetuating cycle of health effects. This is especially relevant in modern times when a variety of factors make it difficult to keep our bodies on their natural timing.

The modern Western diet and other factors in contemporary life already place our gut flora at risk. At the same time, it is more difficult than ever to keep our internal clocks on track. More people have jobs that include shift work or late hours. We are chained to smartphones and other devices that release a wavelength of light that has been proven to disrupt our circadian rhythm. Even if you can control your life to allow optimal sleep, light pollution is serious enough to interfere with your sleep.

The disruption of our circadian rhythms and gut microbiome can be devastating. However, there are ways to keep your body well-regulated.

Keeping Your Internal Clocks — And Those of Your Gut Bacteria — On Track

Keeping your body and your microbiome regulated in the modern world can be a challenge. However, there are several ways to accomplish this. Consider the following tips:

• Practice basic sleep hygiene, going to bed and waking at the same time and turning off screens well before bedtime.
• Use blackout curtains to keep out ambient light if this is a concern in your area.
• Eat meals at the same time every day, to ensure that your gut flora is not dysregulated.
• Take probiotic and prebiotic supplements to ensure that the right bacteria can thrive in your GI tract.
• Avoid taking antibiotics or using antimicrobial products unless completely necessary for your health.

There is still much to discover about the ways that gut bacteria interact with our circadian rhythm. However, it is clear that modern people face an uphill battle in maintaining the right balance. Although it can be difficult to keep your internal clocks, and those of your microflora, on track, doing so is crucial to your health and well-being.