Does your gut microbiome affect how well you sleep?
Your gut microbiome influences your sleep through substances it sends to your brain, and poor sleep in turn disrupts your gut bacteria. A fibre-rich diet and a regular sleep and eating schedule are the best concrete steps you can take right now.
Gut bacteria produce substances that directly influence how you sleep. Think of short-chain fatty acids, serotonin, melatonin and GABA. These substances reach the brain via the so-called gut-brain axis and help regulate sleep. How large that effect is in humans has not yet been established, but several review studies consider the relationship likely to be more than coincidence.
The relationship also works in the other direction. Sleep deprivation and fragmented sleep themselves disrupt the composition of your gut bacteria, possibly because stress hormones are released that throw the gut ecosystem out of balance. In short: poor sleep makes your microbiome less healthy, and a less healthy microbiome makes your sleep worse.
Your daily rhythm plays a major role in this. The microbiome has its own 24-hour rhythm that depends strongly on when you eat. Jet lag, night shifts and an irregular eating pattern dampen those normal daily fluctuations. In both mice and humans, this was associated with glucose intolerance and weight gain. Part of this evidence comes from animal research, so caution is warranted when translating findings to humans.
Probiotics as a sleep supplement sounds appealing, but the evidence for it is thin. A small number of studies report that people subjectively feel more rested, but which bacterial strain, dose or course of treatment works best is unknown. For poor sleepers, a fibre-rich, plant-based diet does more: it promotes the production of sleep-supporting bacterial substances, although there are still few studies that have demonstrated this with actual sleep measurements.
People with sleep disorders also more frequently suffer from diabetes and metabolic syndrome. Research suggests that microbiome disruptions are a shared link, but what is cause and what is effect remains unclear.
This answer rests almost entirely on review studies and systematic summaries of existing research, not on large experiments in which participants were randomly assigned. The interrelationship between the microbiome and sleep is described fairly consistently across these sources, but the exact effect size in humans has not been established in any of them. The evidence for probiotics as a sleep promoter is the weakest: only a small number of studies, with no clarity on which bacterial strain works. The evidence for the circadian rhythm and metabolic consequences is partly based on animal research.
What does too little sleep do to your gut?
Sleep deprivation may disrupt your gut microbiome, but we do not yet know with certainty how large that effect is in humans. Getting good sleep is sensible regardless, for your metabolism and immune system; whether targeted gut intervention produces any benefit in cases of sleep deprivation has not yet been proven.
Does a healthy gut microbiome lead to better skin?
There are several indications that a healthy gut microbiome is beneficial for your skin, but how best to achieve that and which interventions truly work has not been sufficiently proven to recommend specific supplements or treatments.
How does your microbiome affect your health and longevity?
Your microbiome is associated with how healthily you age, but whether you can deliberately steer it to live longer has not yet been proven. A fibre-rich diet and physical activity are currently the most well-supported ways to positively influence your gut flora.
Can your gut microbiome influence how long you live?
There are clear indications that the composition of your gut microbiome is associated with how long and how healthily you age, but whether modifying your microbiome extends your life has not yet been demonstrated in humans.
Can your gut microbiome influence inflammation in your body?
Your gut microbiome can influence inflammatory processes throughout your body via the gut wall. Eating more fibre and exercising regularly are the most well-supported ways to influence this favourably.
Can your gut microbiome affect your cholesterol?
Your gut microbiome influences your cholesterol through bile acid conversion and the fermentation of fibres. Eating more fibre is the most concrete and safe step to take; supplements such as berberine are not yet sufficiently substantiated for daily use.