Ask a Dietitian: Is Poor Gut Health Affecting My Sleep?
There's a reason it's known as our second brain. The health of our gut affects everything – our weight, our mental health, and yes even our quality of sleep. It goes both ways, gut health can affect sleep just as much as sleep can affect gut health.
Quick biology lesson: inside the gastrointestinal tract you'll find the microbiome, which is a complex inner world of billions of different types of bacteria and other living organisms. The composition of these microorganisms inhabiting our gut are as unique in each of us as a fingerprint. In recent years, an increasing number of studies are showing evidence of a microbiome-gut-brain axis. Translation: it's highly likely our microbiome directly affects our mental health, with poor gut health leading to stress and anxiety, which the affects our ability to have restorative sleep each night, and round and round it goes.
Gut health and sleep
Research indicates that the bacteria in our gut and our circadian genes may interact in that poor gut health causes disruptions to our circadian rhythm. It makes sense, given that the intestinal microbiome produce many of the same sleep influencing neurotransmitters as the brain (i.e. dopamine, serotonin and gamma-Aminobutyric acid, aka GABA). One 2019 study concluded there is a strong link between microbiome diversity and sleep efficiency – if your gut has a healthy mix of stuff going on inside it, you're more likely to sleep well.
Plant-based diversity
We know that diversity in the gut microbiome is determined by a number of factors including stress, illness, medication use, genes, and diet, and the two factors we tend to have the most control over are stress and diet. The results from the American Gut Project have also delved into the role of the gut microbiome. In this large-scale study, it was found that those who consumed at least 30 different plant foods per week had the most diverse gut microbiomes and the least antibiotic resistant genes.
Criteria for a healthy gut
1. Fibre
We all know fibre is important to keep us regular, but it's also a crucial factor in maintaining a healthy balance of gut bacteria. Aim to include a diverse range of fibre rich foods into your intake: fruits, vegetables, whole grains, nuts, and seeds. The more variety, the better. Aim for 30 or more of these foods each week!
2. Prebiotics and probiotics
While these can be found in supplements, why not take a food first approach? Prebiotics are the key to good gut bacteria and can be found in most fruits and vegetables in varying quantities. Probiotics are live bacteria themselves that help balance out the less desirable or pro-inflammatory gut bacteria. Your best probiotic food sources are fermented items: yoghurt, kefir, kombucha, kimchi, and sauerkraut.
3. Timing
The digestive tract works hard to break down the food we eat and – just like the rest of our body – it needs time to rest. Aim to finish your last meal (and any snacks) at least two if not three hours before getting into bed each night.
4. Whole > refined
Ultra-processed and refined foods (white bread and sugary items) aren't conducive to good gut bacteria. Not only are they bad in and of themselves, they can also crowd out those fibre-rich wholefoods that are beneficial to gut health.
Explore more content like this in our series, Ask a Dietitian.
Health & Performance Collective is the brainchild of Sydney Dietitians Jessica Spendlove and Chloe McLeod. They use their 20 years of combined knowledge and skills as dietitians to work with motivated people to live and perform at their best.
