It repeats day after day and week after week. We have a schedule for everything: to eat, to work, to exercise, for leisure activities, to sleep… All this spread over the 24 hours of the day, so that we present periodic patterns that are given to us from our ancestors.
To the beat of our internal clock
During the day we remain active and with the arrival of night physiological changes occur that prepare us for sleep. It’s like a clock. An internal clock that warns us that a change is going to take place in the organism and that it is preparing to eat, to sleep, to wake up. receives the name of Cardiac rhtyms.
These refer to all types of changes (physical, mental and behavioral) that are repeated day by day, approximately every 24 hours. It is not difficult to perceive the importance of maintaining them. We have all been at a party late into the night or had days full of tasks without time to eat or sleep properly and have suffered the consequences.
The truth is that the western lifestyle does not help circadian rhythms to be maintained. We enjoy fewer hours of natural light than our ancestors, since we are more sedentary and have considerably increased the number of hours in front of the screens. Added to this is a higher level of stress, a social life that messes up our schedule, and a diet based on sugary and ultra-processed products.
They are factors that significantly alter our natural rhythms. What implications can it have? This mismatch it’s related with lack or poor quality of sleep, mood swings, increased stress, disorientation, memory problems, fatigue and anxiety, among other ills. And if they are maintained over time, they can have much more serious consequences.
Bacteria have their own biorhythms.
But circadian rhythm disturbances don’t just affect us: they also accuse them our gut bacteriawhich have their own biorhythms synchronized with ours. So, can a disorder in the internal clocks affect our intestinal health? Definitely yes.
Disturbances in biological rhythms are closely related to changes in digestion and metabolism. Then there is an imbalance in glucose metabolism and increased risk of weight gain and blood pressure, as well as a deregulation of hormones that control appetite and favor the preference of foods rich in sugars and saturated fats.
This can cause a decrease in insulin sensitivity, a lower glucose tolerance and an alteration of the lipid profile in the body. These are alterations that have a direct impact on intestinal health and, therefore, on the microbiota.
And it is not strange that this relationship occurs, since the digestion of food occurs during the day, at which time the intestine remains active and in optimal conditions to absorb nutrients. When we eat, we put on time the clocks of the organs and tissues involved in digestion: the stomach, pancreas, liver, intestine and adipose tissue.
If we alter the schedules, we alter the microbiota
And what happens to the microbiota if we eat late? For example, having lunch at 4 in the afternoon causes a lag in the clock, a disruption of the normal rhythm of intestinal function and an alteration in the composition and functionality of intestinal bacteria.
The microbiota is mainly affected by the type of diet we follow every day. But altering eating schedules (whether due to eating behavior, fasting, or increasing the frequency of meals) also has an impact on it. Intestinal bacteria present their own fluctuations depending on the time of day, both in composition and in functions.
In fact, the scientific evidence It shows us that they have their own circadian rhythm, which they try to synchronize with their host in order to get the most out of it.
Most of the research on the microbiota and circadian rhythms have been carried out in animals. It should be noted the studies focused on intermittent fasting, which have revealed some benefits in micesuch as increased microbial diversity, reduced inflammation, and production of beneficial compounds by gut bacteria.
In humans, a work carried out with women observed that eating late reverses the rate of oral microbial diversity. Then, on the contrary, a pattern of disease situations appears, similar to that which occurs in obesity or intestinal inflammation disorders.
However, it must not be forgotten that the intestinal microbiota is like a unique and personal signature of each subject, so each person will respond differently to both intermittent fasting and the change in eating schedule.
The influence of microbes on our sleep
These studies show that the intestinal microbiota is affected by a mismatch in biological rhythms, since these activate or deactivate genes involved in bacterial metabolism depending on the time of day. But it is a two-way relationship: the metabolism of intestinal bacteria is also capable of modulating the circadian rhythm.
As it does? Its influence can be given in two ways: by producing metabolites from the food we eat or by responding to jet lag with changes in the abundance of certain bacterial groups.
Thus, the intestinal microbiome is responsible for the production of some of the chemical compounds (the aforementioned metabolites) that end up in our bloodstream and can induce or promote sleep. Bacteria synthesize these substances from the food we eat, and when we eat it, thanks to their own metabolism.
For example, bacteria streptococcus and some strains of Escherichia Y enterococcus contribute significantly to the serotonin production pathway, linked to the sleep-wake cycle. Another neurotransmitter, gamma-aminobutyric acid -from the fermentation of dietary fiber by the microbiota- could promote sleep through an action on the sensory mechanisms of the portal vein of the liver.
Our microbial community can also respond to the disruption of the circadian rhythm or its low quality by modifying the quantity of some bacterial groups. In extreme cases, a state of dysbiosis can be reached, that is, a predominance of harmful bacteria over beneficial ones.
(The Conversation)
