How to use knowledge about light and biorhythms to manage your health and productivity

What does your lab do?

For the last few years, we have been interested in everything related to artificial light. Why is this important? Because humanity, by evolutionary standards, not so long ago began to actively use it — only 150 years have passed. Candles and lamps were burned before, but it was the bright electric light that led to a change in our light regime — the light phase of the day increased. On the one hand, this is not bad, because we live in a strip where there is a chronic lack of light. On the other hand, artificial light accompanies us in the evenings, sometimes even causing harm to the body. How to make it so that the light mode returns to a more or less natural appearance? That’s interesting to explore.

Another direction is chronoepidemiology, that is, the study of exacerbations of diseases associated with the seasons of the year or with the time of day. There are observations that, for example, exacerbation of coronary heart disease, angina attacks and myocardial infarction usually occur in the early morning hours. Moreover, geographical location also plays a role here: for example, in Central Russia, the frequency of exacerbations of coronary heart disease increases significantly in winter, and in Eastern Siberia, on the contrary, in summer.

We are also interested in chronotherapy. It is generally accepted to prescribe medications on the principle of “twice a day” or “three times a day”, but in most cases this is not quite correct. The effectiveness of treatment depends on what time of day the drug enters the body and how this moment correlates with its “biological clock”. And if you find this “right” time for each group of drugs, you can achieve a greater effect with a lower dosage.

What is “biological clock” and why do we need it?

All organisms are constantly forced to adapt to external circumstances, for example, to the change of day and night or the seasons of the year. In order to synchronize with the rhythms of nature gently, there is a special system that we call the “biological clock”. It consists of three levels. The first is cellular: in each cell during the day there may be a different amount, for example, of calcium or sodium — their exchange is regulated by a certain rhythm. The rhythms of all cells are controlled by the epiphysis (pineal gland) — this is the second level. This small gland in the brain produces melatonin and serotonin-the regulators of our sleep and wakefulness, as well as appetite and mood. And finally, the third level — the suprachiasmatic nuclei of the hypothalamus. It is this small group of nerve cells that receives a direct signal from the retina of the eye, which tells the “biological clock” that it is now day or night.

And what rhythms does this mechanism measure?

The most important is the circadian rhythm, which is controlled by more than a thousand different functions of the body: body temperature, blood pressure, hormone production, and much more. It is not equal to astronomical days, but is 24 hours plus or minus 3-4 hours. The fact is that long before the invention of airplanes and trains, it was common for people to travel long distances, and the duration of the light phase of the day in different places on the planet is constantly changing. In such conditions, the biorhythms must be flexible enough to adapt.

Is it true that the “biological clock” differs from person to person and that is why there are “owls”, “pigeons” and “larks”?

Even among chronobiologists, there is a lot of controversy on this topic. It is well known that all chronotypes (both" owls"," pigeons", and" larks") sleep at night and stay awake during the day — this is fixed at the genetic level, and it is impossible to change it. Therefore, it is harmful to work in shifts, when a person leaves the southern region for a month to the Far North, where there is a different light regime, time zone and climatic conditions, and then returns back. He can not avoid desynchronosis — a mismatch of biological rhythms, which is a risk factor for the development, first of all, of cardiovascular and oncological diseases. It is usually accompanied by prolonged increased fatigue, decreased performance and sleep disorders.