Written by Bill Lam (Student Dietitian, Nutrition Coordinator)
Sleep plays a vital role in our overall health and well-being. It is involved in many functions in the body, including supporting healthy brain function, emotional wellbeing and maintaining physical health.
We spend around a third of our lives in our beds to allow our body to rest and recuperate from daily stress and hardship. This ensures we’re ready to perform at our best for the following day. Although most people already know this from first-hand experience, there’s another reason for us to sleep in on those lazy weekends.
Exciting new research on the gut-brain axis has opened opportunities for researchers to investigate the link between sleep and gut health. Based on a recent study by researchers from Nova Southeastern University, poor sleep exerts a strong negative effect on our microbiome diversity. Participants from the study were issued an ‘Actiwatch’ (described as an Apple Watch on steroids) and were required to wear it for 30 days. This novel piece of technology recorded quality of sleep data. A faecal swab was also issued to analyse the abundance and diversity of the gut microbiome using DNA sequencing. The results highlighted that microbiome diversity was positively correlated with increased sleep efficiency (majority of bedtime was spent sleeping). On the other hand, poor microbiome diversity was correlated with time spent awake during sleep. Higher concentrations of healthy gut bacteria were found in participants with greater sleep efficiency, while unhealthy gut bacteria were found mostly in those experiencing poor sleep.
From this, good quality sleep (with adequate hours and little disturbances) is essential to keep your gut in top shape. But it doesn’t stop there. The link between sleep and gut health is bi-directional, meaning that the gut can also affect our quality of sleep. In fact, most of the published research on this topic investigates this direction in particular. However, the mechanisms for this have just been discovered.
New research from the University of Tsukuba found that gut bacteria influence normal sleeping patterns by helping create important chemical messengers in the brain. This includes serotonin and dopamine which are both important in regulating the body’s sleep-wake cycles.
However, the bulk of studies investigating these links originate from animal research. Preliminary human studies show promising results, though, the mechanisms of gut microbiota influencing serotonin/ dopamine production remain unclear.
Researchers found that a low microbiome diversity eliminates serotonin in the gut, leading to low serotonin levels in the brain due to the gut-brain axis. This builds upon a wealth of previous studies that show how a greater microbiota diversity leads to improved sleep quality and lower rates of sleepiness.
Sleep and gut health are both important aspects to our overall well-being. Good quality sleep can benefit gut function, while a healthy diet, that nourishes your gut, can improve your sleep. So what’s stopping you from doing both?
References Smith RP, Easson C, Lyle SM, Kapoor R, Donnelly CP, Davidson EJ, Parikh E, Lopez JV, Tartar JL. (2019). Gut microbiome diversity is associated with sleep physiology in humans. PLOS ONE. 14(10): e0222394. https://doi.org/10.1371/journal.pone.0222394 Ogawa Y, Miyoshi C, Obana N, Yajima K, Hotta-Hirashima N, Ikkyu A, Kanno S, Soga T, Fukuda S, Yanagisawa M. (2020). Gut microbiota depletion by chronic antibiotic treatment alters the sleep/wake architecture and sleep EEG power spectra in mice. Scientific Reports. 10(19554). https://doi.org/10.1038/s41598-020-76562-9 Li Y, Hao Y, Fan F, Zhang B. (2018). The Role of Microbiome in Insomnia, Circadian Disturbance and Depression. Front Psychiatry. 9(669). https://doi.org/10.3389/fpsyt.2018.00669