The Gut-Sleep-Connection: Why Gut and Sleep Health Are Two Sides Of The Same Coin

Do you also tend to think of diarrhea or constipation when you think of intestinal problems and otherwise don’t pay much attention to your gut? 

That may be a little short-sighted because your gut health is so intimately related to things like increasing performance, decreasing sickness, and improving recovery time that a growing number of scientists think that it actually may be the most important organ. 

Some scientists are particularly focused on the relationship between gut health and good sleep, and why it seems to be a key to lifelong health. Let’s take a closer look at why gut health is essential and what it has to do with your sleep.

What is the gut?

The Gut-Sleep-Connection: Why Gut and Sleep Health Are Two Sides Of The Same CoinWhen scientists talk about the gut, they don’t only refer to your intestines. They actually mean the gut microbiome, so everything from your mouth to the entry and exit of your colon, and all the bits in between. That includes your stomach, your small intestine, and your large intestine. 

However, that’s not all! The most important component is the trillions of little critters that live in these areas of your body, like bacteria, fungi, viruses, and cells, collectively known as microbes. You have hundreds of different types of them in your digestive tract, most of them incredibly beneficial and necessary for a healthy body.

Why is it important to have a healthy gut? 

The many bacteria, fungi, and viruses that live together in your gut ideally form a happy community. Having a diverse community of microbes equals having a healthy microbiome, and with that, you can digest food, process nutrients, and train your immune system to function properly.

So gut health is really about long-term health. When you have a healthy gut, you feel more energetic, you get sick less often, you have better mental clarity and, ultimately, emotional well-being. 

In contrast, an unhealthy gut is linked to autoimmune disease, diabetes, neurodegenerative diseases like Alzheimer’s, cancer, and even emotional issues like anxiety and depression. 

And if we now consider what role sleep plays in this system, the first thing to note is that a healthy gut and adequate sleep are two sides of the same coin: your gut microbiome affects your sleep quality and vice versa. So let’s take a closer look at both.

The effect of sleep deprivation on your gut health

We know that sleep is essential for our brain’s function, including learning and memorizing. Lack of sleep has been closely associated with decreased brain function, high blood pressure, diabetes, heart failure, or stroke. This is also why most of the studies looking at sleep deprivation have focused on the function of the brain and the nervous system.

However, in a Harvard study, neuroscientists took another approach. They identified a crucial causal link between sleep deprivation and the increased risk for chronic conditions or even premature death, and the gut.

They found out that when they’ve prevented animals from sleeping, these animals actually die. So the scientist concluded that sleep isn’t only about the brain. Sleep is so essential for survival that a lack of it must cause some kind of life-threatening injury somewhere in the body, other than the brain. And they discovered that the gut was the organ that was explicitly vulnerable to sleep loss.

The toxic effect of stress in your gut

You may know that your body doesn’t properly stop cortisol production, the stress hormone, after you had a terrible night’s sleep. And a higher level of stress hormones messes with the composition, diversity, and number of microbes in your gut. That means the community becomes less diverse, and as a result, more harmful bacteria are lurking around.

But what exactly are these bad bacteria, and what do they do to your body? This is what makes this Harvard study so compelling because the scientists discovered an accumulation of reactive oxygen species (ROS) in the gut of sleep-deprived mice and flies that they didn’t see in the animals’ other tissues. So only their gut accumulated those molecules in very high concentrations. 

What makes ROS so bad is that they are extremely chemically reactive molecules that steal electrons from other cellular macromolecules, destabilizing them and causing oxidative stress. Oxidative stress is so toxic that it can cause severe diseases like chronic inflammation, cancer, Alzheimer’s, and ultimately death.

Why an unhealthy gut makes you craving food 

Another important connection between gut and sleep is that your microbiome seems to be closely intertwined with your sleep-wake rhythm. Therefore, disrupting your body’s internal clock can lead to cravings for unhealthy foods, not only during the day, but also at night. 

In one study, mice were fed a high-fat diet, and the activity of their microbes changed. As a result, the microbes signaled to eat more frequently, and the mice started eating at the wrong times. They had multiple lunches at midnight and became obese. Other mice, who were fed a high-fiber, low-fat diet, didn’t eat at the wrong times and stayed lean. 

So it’s true that your gut microbiome can control you by affecting your digestive and mental health, your mood, your immune system, and your sleep. But you can also somewhat influence your microbiome by the food you eat, the medicines you take, and how you sleep. It’s definitely a dynamic relationship that allows you to act and take improving your health into your own hands.

What makes a healthy microbiome?

To function properly, you need to take things in, digest them, and spit out other molecules that are vital to your health. To be able to execute all these conversion processes, you need a healthy microbiome. 

What makes your microbiome healthy is when it contains very diverse species and bacteria, some that digest veggies, some that digest meats, and some that digest bread and oils, for example.

Let’s say you decide that you are just going to eat foods that are high in fat and carbohydrates, like hotdogs, ice cream, and pizza. If you train your systems to do this, your gut will start using more and more of the type of bacteria that used to see these kinds of foods, and eventually, you’re going to skew the ratios. 

Those bacteria are going to out-compete the other types that are there because they’re just not being used, and then you’ll end up with a situation where you can have a very unhealthy, not diverse set of bacteria in your gut.

Now you might ask if you can reverse that. The answer is yes and no. Some of the bacteria can return, but it often takes a lot of time and energy. And sometimes, you actually can’t reverse things, meaning that once those bacteria are gone, it’s impossible to bring them back.

What are the four biggest causes for an unhealthy gut?

Sadly, many of the things that we do in our lives are utterly lethal to the microbiome. Here are the four biggest causes for an unhealthy gut:

1 – Wrong food. Eating poorly can do two things – first, it can prevent you from getting the nutrients that you need to stay healthy, and second, it can damage and change the entire composition of your gut, which will render it unable to digest things properly and create the nutrients that you need to function.

2 – Antibiotics medicines. No question, antibiotics can be lifesaving, but they don’t just kill harmful bacteria; they kill all bacteria.

That’s why often after you’ve gone through a course of antibiotics, you kill off your microbiome, and sometimes it never rebuilds properly again. But it’s not only the medication you are taking. Remember that the vast majority of antibiotics are used in animal feed, affecting your microbiome and potentially leading to dangerous antibiotic resistance.

3 – Stress. Again, stress is extremely bad for the microbiome. Your central nervous system, your brain is intimately connected to your gut; the two talk back and forth to each other all the time. 

Think about it when you’re stressed; you have a headache, you feel terrible, and you often feel that stress in your stomach like butterflies in your stomach, anxiety, and sometimes you even have to go to the bathroom. That’s a sign that you’re damaging your microbiome. 

4 – Oversensitization. We live in a very aseptic society. No question, hygiene is crucial, but we tend to overdo it. Too much cleanliness decreases the diversity of bacteria in the gut. That’s especially true for children whose microbiome is still developing. 

gut health and children

Back many years ago, children would play in the dirt, and they’d be exposed to all kinds of different things. Now they sit mostly inside, watch TV or play on their phones. There is growing evidence that many diseases like autism and ADHD are connected to the lack of diversity in the gut. Therefore, it’s super important to go outside and get in touch with the environment.

How to improve gut health?

The good news is not all is lost. There are some simple things that you can do to improve your gut. 

The most critical step is eating the right type of food. Did your parents try to impose broccoli or Brussel sprouts off on you when you were a kid? They were actually right because these types of foods contain the essential molecules you have to get from dietary intake to stay healthy – tryptophan, tyrosine, and indole-3 lactic acids (ILA). Let’s look at each of them.


You’ve probably heard of this, Thanksgiving comes, and everybody talks about the tryptophan-induced coma that happens after you have your dinner. Tryptophan is found in Turkey, but it’s also in things like eggs and chia seeds. 

Your body takes tryptophan and converts it into a lot of other vital molecules. One is called serotonin. Serotonin is the key hormone that stabilizes your mood, feelings of well-being, and happiness. The other one is the sleep hormone melatonin. 

So imagine if you don’t have any tryptophan, or you’re not consuming enough tryptophan well, no matter how many roses or chocolates your significant other brings you, it’s just not going to make you happy, and you won’t be able to sleep.


Tyrosine is an amino acid found in foods like almonds, lentils and seeds, and edamame. It is converted to a variety of critical things as well, one of which is dopamine. 

Right dopamine release in your body is crucial because it motivates you to do stuff; it’s this initiative-oriented behavior that helps propel adrenaline, the fight-or-flight molecule that boosts your energy supplies triggers heightened alertness when necessary. 

Indole-3 lactic acids (ILA)

ILA is found in fermented foods, things like pickles, sauerkraut, kimchi, or kefir. ILA is crucial because certain bacteria in the gut convert the ILA into something called IPA, indole-3-propionic acid.

IPA is actually one of the most potent antioxidants in the body. They come in and break down your free radicals, keeping you healthy longer.

Besides changing my diet, what else can I do to improve my gut health?

We’ve talked about the toxic effect that stress can have on your microbiome. Incorporating some simple but effective stress management techniques like mindfulness meditation or breathing exercises into your daily life or making fifteen, twenty minutes of light exercises a habit are great ways to mitigate your stress. These activities also help promote the growth of certain types of bacteria that are necessary for your intestinal functioning. 

And lastly, targeted supplementation. I’m not saying to take lots of different supplements. I’m saying if there are certain things that your body needs, you might take a supplement. One example is omega-3 fish oil supplements; sometimes, there’s a lot of fish you have to eat to get one pill’s equivalency. However, make sure it’s what you need, and don’t overdose.


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