Gut health and sleep - what's the connection?

Gut health is a topic that has gained a lot of attention in recent years. It refers to the balance of microorganisms that live in the digestive tract, which can have a significant impact on overall health. So, what does it have to do with sleep?

The gut-brain axis

One key aspect of understanding this connection is the gut-brain axis. This complex communication network links our gut and brain through the vagus nerve and hormones. Essentially, what happens in our gut can affect our mental state and, subsequently, our ability to sleep.

For example, if the gut microbiome becomes unbalanced, it may lead to increased levels of stress hormones, causing anxiety and restlessness. These conditions can hinder our ability to fall asleep or stay asleep, forming a damaging cycle where poor sleep worsens gut health. A study published in the Journal of Clinical Sleep Medicine 2016 found that a diet rich in saturated fats, sugar and low fibre is associated with lighter, less restorative sleep with more waking.

Furthermore, recent studies suggest that having insufficient vitamin D levels can also have a negative impact on sleep (systematic review 2018). Whilst dietary sources of vitamin D are limited and small amounts may be obtained from mushrooms, egg yolks and liver it may be worth checking your levels via a simple blood test with your GP or preferred health practitioner.

The gut and sleep are two interconnected systems that work together. The gut plays a critical role in regulating the body’s circadian rhythm, which is the internal clock that helps control sleep and wake cycles. The gut microbiome produces a variety of hormones that can influence sleep, including serotonin, which is also a neurotransmitter that regulates mood and sleep.

More recently, research published in 2019 suggests that improving gut microbe diversity could promote better sleep.

 Tips to improve gut diversity and better sleep

• Eat lots of fibre and focus on whole grains: whole wheat pasta, brown rice, brown bread/sourdough, quinoa.
• Try foods rich in probiotic cultures: natural yoghurt, kefir, kombucha, green peas, apples.
• Eat a rainbow: add as many colours as possible to your daily diet.
• Avoid deep-fried, heavily processed foods and cut down on sugar.
• Exercise regularly, even one daily walk outdoors can promote the growth of friendly bacteria in your gut.
• Have a good sleep routine with regular sleep and waking times; aim for similar times each night and morning.
• Enjoy daylight to establish a healthy circadian rhythm.
• Hydrate.
• Avoid strenuous exercise at least two hours before bedtime.

References

• St-Onge, M. P., Roberts, A., Shechter, A., & Choudhury, A. R. (2016). Fiber and Saturated Fat Are Associated with Sleep Arousals and Slow Wave Sleep. Journal of Clinical Sleep Medicine: JCSM: official publication of the American Academy of Sleep Medicine, 12(1), 19–24. 
• Smith, R. P., Easson, C., Lyle, S. M., Kapoor, R., Donnelly, C. P., Davidson, E. J., Parikh, E., Lopez, J. V., & Tartar, J. L. (2019). Gut microbiome diversity is associated with sleep physiology in humans. PloS one, 14(10), e0222394 
• Gao Q, Kou T, Zhuang B, Ren Y, Dong X, Wang Q. The Association between Vitamin D Deficiency and Sleep Disorders: A Systematic Review and Meta-Analysis. Nutrients. 2018 Oct 1;10(10):1395. doi: 10.3390/nu10101395. PMID: 30275418; PMCID: PMC6213953