The Link Between Gut & Sleep
The surprising link between gut health and sleep
It’s well established how important a good night of sleep is for our overall physical, mental and emotional wellbeing. I’m sure you’ve experienced the brain fog, fatigue and lack of concentration that follows a night of restless sleep.
The microbial cells in our digestive system (also known as the gut microbiome) have a large role in supporting our overall health and wellbeing, as they absorb nutrients from the food we eat, produce immune system molecules, influence metabolism, and produce neurotransmitters and other key molecules for our health. Put simply, the more diverse the microbiome, the better your overall health.
The composition and diversity of the gut microbiome is affected by a number of factors including diet, environment, genetics, age, geographical location, stress, temperature, medication use, and other factors.
How is gut health related to sleep?
The brain-gut-microbiome axis is the name for the highly-complex bidirectional relationship between the gastrointestinal tract and the brain. The gut and brain are directly connected via the vagus nerve, and each has a profound impact on the other. A number of studies have identified that the relationship between the brain and gut can have a significant impact on the quality and quantity of your nightly slumber.
One particular study found that increased microbiome diversity in the gut environment is related with increased sleep efficiency and total sleep time. The same study found that sleep deprivation negatively affected the microbiome, leading to dysbiosis (or an imbalance in the microbiome), and increased intestinal permeability (sometimes referred to as “leaky gut”)3.
Sleep hormones
The gut microbiome is directly involved with the production of two key sleep hormones – serotonin and melatonin.
Melatonin directly controls the body’s circadian rhythm – also known as the sleep-wake cycle. Production of melatonin typically increases at night time in response to darkness to promote sleepiness, and is suppressed with exposure to light. Melatonin helps to align the body’s sleep-wake cycle with the rhythms of day and night.
Serotonin is well known for its role in supporting mood and emotional regulation, however it also has an important role as the precursor to melatonin. The majority of the body’s serotonin is produced by the microbial cells of the gut. Therefore, any bacterial imbalances in the gut are linked with serotonin and melatonin alterations, and therefore mood and sleep changes.
Sleep apnoea
Obstructive sleep apnoea is characterised by periods of reduced oxygen supply during sleep, usually caused by airway obstruction. The lack of oxygen allows pathogenic microbes in the gut to proliferate, causing dysbiosis (or an imbalance in the beneficial species within the gut). Sleep apnoea is also linked with increased inflammation in the intestinal barrier, increased ‘leaky gut’, and increased numbers of circulating endotoxins and other inflammatory molecules.
In another study, children who snore were found to have a lower microbial diversity and richness, and a higher abundance of proinflammatory bacteria compared with children who don’t snore2. People who snore typically note that they do not feel well-rested upon waking. The study also noted that breastfeeding is potentially protective against snoring, due to the microbial colonisation in the gut that breastfeeding supports.
Social jetlag
A study was published this month in the European Journal of Nutrition about the link between "social jetlag" and changes to the composition of the gut microbiome1. Social jetlag refers to the adjustment made to sleep cycles according to work schedules - such as waking up earlier on weekdays and sleeping in on weekends.
In this study they found that small shifts in sleep patterns across the week are linked to differences in gut bacterial species. They also found that social jetlag was associated with lower overall diet quality, higher intakes of sugar, and lower intakes of fruits and nuts, which may directly influence the abundance of specific microbes in the gut. This is likely because sleep impairment affects daytime dietary choices, including disruption of appetite regulation and changes to the secretion of the hormones that regulate appetite and hunger cues.
So does gut health affect sleep quality, or does quality of sleep affect gut health?
As discussed above, the gut-brain axis is a bidirectional pathway, where the gut microbiome influences sleep patterns, and sleep, in turn, affects gut health. In other words - we can’t improve the health of one without thinking of the other!
How to support your gut health to improve your sleep (and vice versa!):
• Maintain a regular sleep-wake pattern over the entire week including weekends to reduce social jetlag.
• Support your gut health by limiting the amount of sugary snacks, processed foods and refined carbs, and increasing your consumption of fresh fruits, vegetables, wholegrains, nuts and seeds.
• Probiotic supplementation – certain strains of probiotics act on the brain–gut–microbiome axis to support stress, brain function and sleep quality.
• Fermented foods contain naturally occurring probiotic species, and includes foods such as kimchi, sauerkraut, kefir, kombucha, tempeh, apple cider vinegar, and some pickles.
• Tryptophan is the amino acid which is the precursor to serotonin and melatonin. Quality sources of protein and complex carbohydrates (such as brown rice, oats, wholegrains), peanuts and bananas provide tryptophan.
• Reduce alcohol consumption at night – alcohol affects the body’s ability to get rapid eye movement (REM) sleep in the second half of the night, and also causes frequent waking in the second half of the night. Alcohol also negatively impacts the composition of the microbiome and reduces the amount of available tryptophan.
• Reduce stress. Exposure to stress can negatively affect sleep, the sleep/wake cycle and causes dysbiosis of the microbiome. Cortisol is a hormone secreted in stressful conditions and is known to affect the integrity and motility of the gut, which may also affect the composition of the microbiota. Stress can be reduced by any self-care practices that you enjoy, or yoga, meditation, herbal medicines, and breathwork practices.
• Magnesium helps to reduce stress, promote calm, and reduces the time taken to fall asleep. Magnesium can be found in dark leafy greens such as kale and silverbeet, black beans, kidney beans, legumes, almonds, peanuts, cashews, sunflower and pumpkin seeds, and bananas.
There is a strong bidirectional relationship between gut health and sleep. A balanced gut microbiome positively impacts sleep, while healthy sleep patterns, in turn, support gut health. This confirms the importance of nurturing a diverse and balanced gut microbiome through dietary and lifestyle changes to promote restful and restorative sleep, and therefore contributing to overall well-being and mental health. If you’re experiencing gut issues, it may be worth considering if your sleep could be improved. Alternatively, if you’re waking feeling unrefreshed and not getting deep, restful sleep each night, you may wish to consider working on improving your gut health. Naturopaths see the body as an interconnected ecosystem, and restoring balance to one aspect of your health will improve the overall health of other parts.
So, if you want a better night’s sleep, want to wake up feeling refreshed and energised or are just curious how much your gut health is affecting your overall wellbeing then I’d love to help.
At a consult we would look at some or all of:
• making achievable tweaks to your diet to give your gut more of the nutrients it needs
• testing to evaluate the current health of your gut microbiome
• selecting specific probiotics and prebiotics to balance your microbiome
• identifying ways to help you de-stress
Written By Emily May
Naturopath
References:
1. Bermingham KM, Stensrud S, Asnicar F, Valdes AM, Franks PW, Wolf J, Hadjigeorgiou G, Davies R, Spector TD, Segata N, Berry SE, Hall WL. Exploring the relationship between social jetlag with gut microbial composition, diet and cardiometabolic health, in the ZOE PREDICT 1 cohort. Eur J Nutr. 2023 Aug 2. doi: 10.1007/s00394-023-03204-x. Epub ahead of print. PMID: 37528259.
2. Collado, Maria Carmen; Katila, Maija Kristiina; Vuorela, Nina Maria; Saarenpää-Heikkilä, Outi; Salminen, Seppo; Isolauri, Erika. Dysbiosis in Snoring Children: An Interlink to Comorbidities?. Journal of Pediatric Gastroenterology and Nutrition 68(2):p 272-277, February 2019. | DOI: 10.1097/MPG.0000000000002161
3. Naufel MF, Truzzi GM, Ferreira CM, Coelho FMS. The brain-gut-microbiota axis in the treatment of neurologic and psychiatric disorders. Arq Neuropsiquiatr. 2023 Jul;81(7):670-684. doi: 10.1055/s-0043-1767818. Epub 2023 Jul 4. PMID: 37402401; PMCID: PMC10371417.
4. Neroni B, Evangelisti M, Radocchia G, Di Nardo G, Pantanella F, Villa MP, Schippa S. Relationship between sleep disorders and gut dysbiosis: what affects what? Sleep Med. 2021 Nov;87:1-7. doi: 10.1016/j.sleep.2021.08.003. Epub 2021 Aug 18. PMID: 34479058.
5. Smith RP, Easson C, Lyle SM, Kapoor R, Donnelly CP, Davidson EJ, Parikh E, Lopez JV, Tartar JL. Gut microbiome diversity is associated with sleep physiology in humans. PLoS One. 2019 Oct 7;14(10):e0222394. doi: 10.1371/journal.pone.0222394. PMID: 31589627; PMCID: PMC6779243.
6. Thompson, R.S., Roller, R., Mika, A., et al.Dietary prebiotics and bioactive milk fractions improve NREM sleep, enhance REM sleep rebound and attenuate the stress-induced decrease in diurnal temperature and gut microbial alpha diversity. Front Behav Neurosci, 10 (2016), p. 240, 10.3389/fnbeh.2016.00240
