Is Gut Health Keeping You Up at Night?


Wondering how your gut microbiota could be involved in sleep changes when the clocks Spring forward this week? How are our gut bugs going to feel about losing that one hour of sleep?

This blog has got it all covered – it looks at how biological rhythms and the microorganisms in the gut may impact how our bodies adjust to British Summer Time. 


Circadian Rhythm

So, what is our biological rhythm and why might the gut microbiota be involved? The biological clock is also known as the circadian rhythm. Circadian rhythms regulate our sleep patterns and sleep cycles, responding to daylight and night-time. Sleep cycles are also known as the sleep-wake cycle and refer to the 24-hour day-night cycle where periods of biological activity alternate with restfulness.


Factors Affecting the Gut Microbiota (5)

Circadian Rhythm and the Gut Microbiota


These day and night cycles are the most important cue for our central clock as human beings, and they are also important for our gut clock – our gut bacteria have their own daily rhythm when it comes to functions, composition, and location in the intestines.1


There appears to be a link between circadian rhythm and the gut microbiota, and a higher ratio of Bacteroidetes to Firmicutes is shown to be related to an increase in sleep deprivation.2


Carasso et al. identified, through 91 participants, that those who had a greater percentage of light exposure during the day had a higher Shannon index (a measure for diversity of bacteria in the gut microbiota), and that those who went to sleep later (i.e., reducing the proportion of light to dark in their day) had a less diverse microbial community.3 They also found a significant correlation between those who go to sleep earlier and those who have higher adherence to a healthier diet.


A small study investigated the differences in the gut microbiota of rotational shift workers when working the day versus night shift. In 10 security workers (age; 25–40-year-olds), the researchers observed a reduction in Bacteroidetes during the night-shift period, compared to an increase in Actinobacteria and Firmicutes when they worked the day shift. These microbial differences in night-shift workers were linked to a cardiac rhythm disturbance, which in turn, the authors noted could be related to increased metabolic syndrome risk in these individuals.4 Further research is needed in this area.

Dietary Patterns, Circadian Rhythm and Food Choice


A recent clinical review summarises how the impact of circadian rhythm could be related to food patterns. They explained that dietary stressors such as alcohol or fat exacerbated the gut microbiome disturbances caused by circadian disruption. This was a similar observation for those on a high sugar and fat diet, with results showing circadian disruption and, in turn, a significant reduction in gut microbiota diversity.5 Therefore, it could be suggested that a diet lower in fat and sugar and higher in fruits and vegetables could increase gut microbiota diversity, together with specific probiotic supplementation which could, in turn, help to decrease sleep disruption.


Additionally, the evidence in this area suggested that altered sleep/wake cycles have an increased influence on meal patterns and circadian disruption, as food is the primary source of microbial diversity. In practice this could suggest focusing on a balanced diet with patients to support the gut microbiota while there are disruptions to their circadian rhythm.


Interestingly, Nishida et al., explored whether long-term use (24 weeks) of a bacterial strain, Lactobacillus gasseri CP2305, would improve stress-associated symptoms in healthy young Japanese men and women (n=60 medical students) preparing for an exam, in a randomised double-blind placebo-controlled study. Intake of the probiotic tablet significantly reduced anxiety and sleep disturbance relative to placebo. In addition, gene sequencing measures showed probiotic administration attenuated the stress-induced decline of Bifidobacterium spp. and the stress-induced elevation of Streptococcus spp.6


Additionally, in a pre-clinical study looking at sleep disturbances and the gut microbiota, it was found that administering the probiotic PS150TM in mice improved their sleep, even when they had sleep disturbance influenced by caffeine. 7 Although this provides interesting insight into the potential use of probiotics in sleep disturbances, further research is needed in human populations to confirm these results. Interestingly, research on prebiotics demonstrates that early-life supplementation maintains nap and daytime waking states but larger, longer-term studies are still required.8


This is a growing area of science, and more research is beginning to emerge which explores the microbiota-gut-brain axis and how this contributes to the regulation of sleep behaviour, both directly and indirectly. A review by Wang et al. explores more deeply how sleep deprivation leads to dysfunction of gut microbiota and discusses how sleep disorders are accompanied by altered gut microbiota composition.8


Take-home Message


But back to the BST clock change – how does our gut microbiota play a role in circadian rhythm changes during this clock change? With only one hour change, there might be little difference in gut diversity changes, but keeping a balanced diet with food supporting gut microbes like fibre and plant diversity could be a good place to start. There is emerging evidence on sleep and the role of supplementing the diet with prebiotics and probiotics. More research is still needed on circadian rhythms and how diet and lifestyle could impact our internal body clock.


By Nutritionists at Yakult Science UK & Ireland, Dr Emily Prpa PhD & Brittany Pearse ANutr.


1.    Parkar, S.G., Kalsbeek, A. and Cheeseman, J.F., 2019. Potential role for the gut microbiota in modulating host circadian rhythms and metabolic health. Microorganisms, 7(2), p.41.

2.    Matenchuk, B.A., Mandhane, P.J. and Kozyrskyj, A.L., 2020. Sleep, circadian rhythm, and gut microbiota. Sleep medicine reviews, 53, p.101340.

3.    Carasso, S., Fishman, B., Lask, L.S., Shochat, T., Geva-Zatorsky, N. and Tauber, E., 2021. Metagenomic analysis reveals the signature of gut microbiota associated with human chronotypes. bioRxiv, pp.2021-03.

4.    Mortaş, H., Bilici, S. and Karakan, T., 2020. The circadian disruption of night work alters gut microbiota consistent with elevated risk for future metabolic and gastrointestinal pathology. Chronobiology international, 37(7), pp.1067-1081.

5.    Parkar, S.G., Kalsbeek, A. and Cheeseman, J.F., 2019. Potential role for the gut microbiota in modulating host circadian rhythms and metabolic health. Microorganisms, 7(2), p.41.

6.    Nishida, K., Sawada, D., Kuwano, Y., Tanaka, H. and Rokutan, K., 2019. Health benefits of Lactobacillus gasseri CP2305 tablets in young adults exposed to chronic stress: a randomized, double-blind, placebo-controlled study. Nutrients, 11(8), p.1859.

7.    Lin, A., Shih, C. T., Huang, C. L., Wu, C. C., Lin, C. T., & Tsai, Y. C. (2019). Hypnotic effects of lactobacillus fermentum PS150TM on pentobarbital-induced sleep in mice. Nutrients, 11(10), 2409.

8.    Wang, Z., Wang, Z., Lu, T., Chen, W., Yan, W., Yuan, K., Shi, L., Liu, X., Zhou, X., Shi, J. and Vitiello, M.V., 2022. The microbiota-gut-brain axis in sleep disorders. Sleep Medicine Reviews, p.101691.