Mastering the Microbiome: October 2022
This month's topic: the effects of sleep on the microbiome
Welcome!
This month, we look at how the microbiome impacts - and is affected by everything from the way you sleep to the type of coffee you drink in the morning. Read on to learn how research is advancing in the field.
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Research Map
A. Coffee Eases Ill Effects of Sleep Deprivation
Sleep deprived? Just drink coffee. No not really - you should actually get some sleep. But coffee may help cancel out the effects of sleep deprivation.
Here’s why. Scientists at the Shanghai University of Traditional Medicine found that when rats were deprived of sleep, the gut microbiome became disordered, and depression systems commenced. But just add coffee, and the microbiome starts to return to normal. At the same time, the researchers saw depression-like behaviors decrease. Both regular and decaf will do (though regular coffee seems to reduce depressive behaviors more).
Featured Article: The Impact of Instant Coffee and Decaffeinated Coffee on the Gut Microbiota and Depression-Like Behaviors of Sleep-Deprived Rats 🇨🇳
It is known that symptoms of depression and the gut microbiome disturbances are linked - so it makes sense that adjusting one could help the other. But more research is needed to figure out exactly how the two issues relate on a biological level. In related news…
The study described in the paragraph above, which found a link between levels of certain bacteria in the microbiome and depression, also found links between the microbiome, certain gene variants, and other diseases like colorectal cancer. 🇦🇺🇫🇮🇬🇧🇺🇸
The group featured in this summary for its coffee-related research had earlier shown that sleep deprived rats exhibited depression-like behaviors and microbiome changes - providing the impetus for the featured study. 🇨🇳
And more on the topic of sleep deprivation, research on mice finds that males and females may respond differently. One study has shown that while female mice display anxiety and depression-like behaviors right after an episode of sleep deprivation, for males it tends to take these symptoms a day or two longer to set in. 🇲🇽
B. How Sleep Apnea Impacts the Gut Microbiome
Sleep apnea affects nearly 1 billion people globally. Recent microbiome research suggests that the gut microbes may play a role in the broader metabolic symptoms of sleep apnea.
Chinese researchers probed further the known impact that the gut microbiota has on liver and fat tissue in cases of sleep apnea. Mice were subjected to chronic intermittent hypoxia or chronic sleep fragmentation - both common features of sleep apnea - for 10 weeks (and compared to mice who were allowed normal sleep). Mice subjected to these sleep apnea conditions saw not only changes to the microbiome, but also changes to the structure of the liver and significant weight loss.
Featured Article: Effects of Chronic Intermittent Hypoxia and Chronic Sleep Fragmentation on Gut Microbiome, Serum Metabolome, Liver and Adipose Tissue Morphology 🇨🇳
Obesity is a major risk factor for sleep apnea. While this featured study explains how sleep apnea impacts the microbiome, other researchers are investigating the reverse: how different treatments could bring about weight loss via microbiome alterations:
One group of scientists investigated how Sangguayin Decoction, a medicinal plant mixture, might improve metabolic syndrome in mice with high-fat diet-induced obesity through gut microbiota alterations 🇨🇳
Meanwhile, whole grain Qingke was demonstrated to have an anti-obesity effect (for mice given a high-fat diet), also by altering the fecal microbiome 🇨🇳
Amplodipine, a medicine often used to treat high blood pressure, was recently found to have mitigating effects on non-alcoholic fatty liver disease through microbiome changes 🇨🇳
C. Exploring the Sleep-Brain-Gut Axis in Infants
How infants sleep likely impacts their gut microbiome - and their long term growth and development.
That is the finding of a European research team, who identified several links between sleeping patterns and the microbiome in infant children. Infants who slept more during the day tended to have a less diverse microbiome. Fragmented nighttime sleep was more common in infants with a more ‘mature’ microbiome (just as a child’s reading score may be high for their age, a young infant’s microbiome - say 3 months old - may resemble more closely that of older, 6 month old infants than fellow 3 month olds). Finally, and maybe most significant for long-term health, sleep behavior and microbiome changes are both correlated with patterns of activity in the brain - impacting how the infant brain matures.
Featured Article: From Alpha Diversity to Zzz: Interactions among sleep, the brain, and gut microbiota in the first year of life 🇨🇭🇩🇰
The researchers conclude that getting adequate sleep at a very early age could help promote lifelong good health. But even if you are no longer an infant (that’s pretty much guaranteed if you’re reading this newsletter), the young field of ‘sleep-brain-gut’ axis research may bring sleep recommendations or microbiome-targeting therapies to improve your sleep and boost the many other aspects of health that depend on it. In related news…
A group of researchers studied the microbiomes of nearly 2000 young infants (1-3 years old) from 17 countries. They found that the infant microbiome evolves a certain way, with an early microbiome dominated by Firmicutes and Bifidobacterium bacteria transitioning to a microbiome where Bacteroides and Prevotella species are more common. 🇨🇳
A second study found a link between the microbiome and insomnia. Using machine learning models, they identified two key bacteria that differentiate insomnia patients from the general population. 🇨🇳
A third has shown that in young, healthy adults (between 20 and 40 years of age), poorer self-reported sleep quality was associated with a lower microbiome diversity - and the altered abundance of certain bacteria. 🇺🇸
D. Chronic Sleep Fragmentation Disrupts the Gut Microbiome
Many nights we toss and turn, dreaming for a better night’s sleep. Does fragmented sleep impact the gut microbiome?
Researchers at the Air Force Research Laboratory created a rat model in which human feces (and the microbes that come with them) were transplanted into rats whose own microbiomes were first depleted with antibiotics - a way to see how the human microbiome would respond to experimental conditions without needing to subject humans to sleep deprivation. The rats were subject to acute sleep fragmentation (6 days) or chronic sleep fragmentation (6 weeks). Researchers found only chronic sleep fragmentation significantly decreased the overall diversity of microbes in the intestine - though acute sleep fragmentation did change the abundance of certain select populations of microbes.
Featured Article: Identification of sleep fragmentation-induced gut microbiota alteration and prediction of functional impact in Sprague Dawley rats harboring microbiome derived from multiple human donors 🇺🇸
How exactly this affects gut health in general (and the health of other organs is still an open question), but there is certainly no lack of research in this area, as this month’s featured studies demonstrate In related news…
Scientists have assessed another external stimulus — food — to see its impact on the gut microbiota. One research team investigated rhubarb and its effects on bacterial diversity in feces and bowel mucosa of rats. 🇨🇳
Another group of scientists researched how probiotics, inulin, or a combination of the two impact the piglet microbiota at different locations in the intestine. 🇦🇹
Sleep, diet, and medications are all external factors. What about internal ones? Researchers in India investigated the impact of genetics on the microbiota of growing pigs. 🇮🇳
Research Community
This month’s research involved researchers in 9 countries - including 7 US states
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