Autumn, what will happen to us tomorrow
How does the human body react to the approach of winter and is there any way to help it
Polina Loseva, "The Attic"
As the daylight hours decrease, many animals go into hibernation, and people begin to feel sleepy and dull. How is this related to the lack of sunlight? And does this mean that physiologically we weaken in winter? "The Attic" has compiled a short guide to human biological rhythms and tells why and where they can move.
Is biorhythms a change of sleep and wakefulness?
Not quite. Biorhythm (or circadian rhythm) is a cycle by which physiological processes in the body replace each other. The usual sleep and wake cycle is the circadian rhythm of the central nervous system. But the clock is ticking on deeper levels as well. For example, about 10% of the genes expressed in each cell of the body do it cyclically (that is, the peak of expression occurs at a certain time of day). At the same time, only 1-3% of these genes are common in cells of different types, say liver and heart, the rest are responsible for organ-specific functions.
The difference between day and night is known to every cell of our body. Firstly, during the day, ultraviolet radiation acts on them, which means that DNA damage accumulates. This is especially true for skin cells, which would be more profitable to share at night, so as not to multiply mutations. Secondly, the cells get more food during the day. That is why they also have to be shared in the daytime, despite the danger. Thirdly, during the day most of our organs work more intensively – blood vessels, muscles, kidneys, liver. Therefore, cells are comfortable with a regime in which some genes are active during the day and others at night.
And the brain controls them all?
This is also not quite true. Each cell has its own circadian rhythm – a peripheral clock, for the discovery of which the Nobel Prize in Physiology or Medicine was awarded in 2017. In short, they are arranged as follows: there are activator genes, and there are repressor genes. The former activate the latter, and the latter encode repressor proteins. When a lot of proteins accumulate, they completely stop the work of activator genes. But gradually the repressor proteins disintegrate, and then activator genes begin to be expressed again. Thus, the system regulates itself. Activator genes and repressor genes trigger the work of other genes, putting the cell into a "day" or "night" mode.
The role of the brain in these processes is rather guiding. It does not so much support the rotation of cycles as it synchronizes phases throughout the body.
Why is there a desynchronization and what does it threaten?
Most of the body's cells sit deep in our body and do not see white light. Therefore, they have to judge the time of day by indirect evidence, for example, by the temperature of the surrounding tissue and the availability of food. Depending on how well they are heated and how long ago they were last fed, the cage "twists" its clock. Therefore, when we start eating or exercising at night, peripheral biorhythms are rearranged. Cellular morning comes at night, and by the present morning activity drops. And when food appears again, already planned, the cell is not ready to absorb and digest it.
It is not surprising that recently many diseases have been associated with a malfunction in circadian rhythms: from metabolic disorders to obesity, diseases of the cardiovascular system and cancer. For example, it turned out that in cancer cells, the peripheral clock is suppressed, probably so as not to interfere with these voracious egoists to consume food without interruption around the clock.
How do I sync everyone back?
This requires a central clock, the same ones that work in the brain. The role of the clock is played by a group (about 20 thousand) neurons located in the suprachiasmatic nucleus of the hypothalamus. Each of the neurons has its own peripheral clock (activator genes and repressor genes), but the impulses that they can generate on their own are rather weak. Under the influence of light, other neurons are activated – in the retina of the eye, which send a signal to the hypothalamus and stimulate the neurons of the central clock, as a result of which the impulses become stronger. All these 20,000 cells are closed in a network that ensures the purity of the signal and a clear periodicity.
At the output, the central clock generates an impulse that signals the body about the time of day. We do not yet know exactly how daytime signals differ from night signals – whether by force, frequency, or something else, but you can imagine a clock that beats loudly during the day and ticks barely audibly at night. Different parts of the brain respond to the signal. One of them – the pineal gland, or pineal gland – stops releasing melatonin, which we know as the "sleep hormone", under the influence of an impulse. And then the presence / absence of melatonin together with the signals of the autonomic nervous system (which controls the activity of internal organs) stimulate or inhibit the work of genes in individual cells.
Is it possible to live without light?
When the central clock does not work, each organ begins to live on its own. And often the pack, deprived of a leader, does not cope with synchronization. This is indicated, for example, by studies of blind people. Almost half of the blind biorhythms go into free swimming (free running): people spontaneously fall asleep during the day and suffer from insomnia at night, the concentrations of regulatory hormones - melatonin and cortisol – do not correspond to the time of day. This condition can be compared with a permanent jetlag: the body, no matter how hard it tries, cannot keep up with the times. Desynchronization can occur even with a clear social rhythm – the daily regime of food and activity. This means that light is the strongest inducer of our biorhythms – other factors only complement it.
Similar difficulties await people living close to the poles. Research was carried out on the staff of the research station in Antarctica, where almost a third of the year is the polar night and, therefore, the sun cannot start biorhythms, and the other third of the year is the polar day and the sun, on the contrary, does not set. It turned out that it was easier for people to cope with the night: you can turn on the light in the room and feel like during the day. But on a polar day, it is much more difficult to simulate the night, especially for night shift workers who have to go outside. One way or another, without maintaining a normal light regime, problems arise for sighted people, but deprived of the solar cycle.
What will become of our rhythms in winter?
Many people complain of insomnia in the middle of winter (midwinter insomnia). This is more typical for northern latitudes, in particular for Russia (81% of men and 77% of women!). It is believed that the matter is in the absence of a clear light stimulus in the morning: you have to get up after dark, the body swings slowly and the circadian rhythm shifts forward, so you start to want to sleep later, hence insomnia.
However, it also depends on the place of residence. In large cities, rhythms are generally shifted forward more often than in rural areas, due to artificial lighting. This effect is also reproduced in the hunter-gatherer tribes of Argentina, who gain access to electric light. Therefore, residents of large cities may not notice the changes so much.
It should be borne in mind that other factors, such as age, also affect the individual circadian rhythm. In adolescence (between 10 and 20 years), the cycles shift forward, before and after this period they are much closer to the natural light day. Marital status also plays a role: mothers often adjust to their young children, and spouses – to each other.
I am an "owl" and used to live in the dark. Will it be easier for me in winter?
As sad as it sounds, "owls" are generally more difficult in life. In these people, late rhythms are determined genetically: their repressor protein differs from that of "larks", therefore, it decays in the cytoplasm at a different rate. As a result, the cycle strives to "leave" away. And considering that "owls" get up later on average, they react less to morning light stimuli. And the rhythms are generally less stable. Therefore, "owls" are more prone to various diseases like diabetes and obesity, it can be more difficult for them to study or drive a car, and people with unstable mentality are more common among them.
How to help the body survive the winter?
The main thing is to accept. The rhythm will move, which means that drowsiness or absent-mindedness may occur. To smooth out transitions, it is useful to set up your own light mode and constantly maintain it. There is also a more radical, but no less effective option – to go camping. A week of camping in nature perfectly synchronizes the biorhythm with the natural light day, the recipe is proven. In addition, it is important to remember that there are many clocks in our body and anyone can run ahead or fall behind. Therefore, it is not necessary to confuse individual organs from the right path, giving them temptations in the form of night snacks and discos.
Portal "Eternal youth" http://vechnayamolodost.ru