Russian pianist and composer Alexander Scriabin once said: “I am the memory of an enlightened eternity, I am not affirmation, I am ecstatic.” His contemporary, the Valencian painter Joaquín Sorolla, was drawn by light in fleeting impressions of what would later paint on a flawless canvas. Mythological is also the shadows that fall into the depths of Plato’s cave, which never stops trying to find the light that guides human knowledge.

From the first explosion big BangIn a universe in which the seasons, equinoxes, solstices, the continuous evolution of day and night follow each other, the abstraction implied by the idea of ​​brushing against infinity, the promise of an endless cyclical turn that forms the basis of the present possibility of contemplation.

In this rhythmic sequence of events, mankind began to search for its niche on Earth, just as the planet took its place in the unimaginable vastness of the universe. And he began to play in a race against time, in favor of the light. That’s right, light expresses our daily life with an astonishing ability as one of the main stimuli that coordinate, regulate and synchronize our organic activity over time.

cardiac rhythms

British evolutionary biologist William Hamilton argued that the conservation of a species depends on its versatility and that only those that have changed stay true to themselves and we can add them to the surrounding environment. Evolution has matched the changing state of the outside world to the inner workings of living things in cyclical fluctuations over time known as circadian rhythms.

Circadian rhythms are cycles of endogenous regulation that last about 24 hours. circadian comes from latin approximatelyWhat does that mean about a day-. They arise as an evolutionary adaptation that allows us to anticipate, anticipate changes in the environment in order to respond more effectively.

These rhythms guide or dictate processes in animals and plants such as hibernation, courtship and reproduction, weight changes or hormonal changes. They also control important processes in humans with their molecular effects (gene expression), metabolic, physiological (regulation of body temperature, heart rate, sleep and production of melatonin, insulin, glucagon) and behavioral (mood, functions and cognitive activity).

How do we get light information?

The most spiritual minds and souls would say, “We are beings of light.” For us mammals, the shift between light and dark, controlled by the day/night binomial, represents, as we have said, the most important regulating signal of our circadian rhythms.

The suprachiasmatic nucleus, a small structure located in the anterior hypothalamus, one of our brain regions, works as a master clock, or central clock, by monitoring the intensity of the light we receive.

This stimulus is also perceived at the ocular level, in the retina, and through the retinohypothalamic pathway (eye-brain pathway), the information that is responsible for controlling the functions of our peripheral organs through regulation flows to the aforementioned nucleus. It inhibits the release of hormones such as melatonin.

Through this sequence of events, the conductor coordinates the suprachiasmatic nucleus, the peripheral organs with the stick in hand, the instrumentalist subjects.

Evolution of the circadian system

The regularity in the internal temporal order of man requires a maturation process from birth to adulthood.

The fetus, which is strongly attached to the mother, constantly receives the cyclical signals she produces, informing, for example, the time of day/night relative to circulating melatonin concentrations in the blood. Fetal circadian rhythms such as melatonin and cortisol are still mostly regulated by the mother.

Birth is a critical moment. New neural connections are established within the suprachiasmatic nucleus and to other parts of the already independent newborn’s brain, which must gradually adapt to the new environmental signals to which it is exposed.

At three months of age, sleep-wake rhythms begin to solidify. At two years, it reaches the maximum nerve connections of the central clock. In the first years of life, circadian rhythms will reach the daily periodicity that characterizes the adult stage.

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light-dark-disease

When our ancestors homo sapiens After deciding to hunched her back from her upright posture and prostrate in front of the computer, we stepped into the global, technological, and overstimulated world that rules us. In our current lifestyle, we often go in the opposite direction of what our circadian rhythms (sleep-wake cycle disruption, eating at odd hours, exposure to artificial light at night) dictate, and this is what we call chronodisruption.

It is believed that these behavioral patterns may be closely related to the risk of developing diseases such as cancer. In fact, the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) have classified shift work (where the light/dark, sleep/wake cycle is continuous over time) as a possible human carcinogen.

The unbalanced ticking of the circadian clock will predictably have more serious effects on organs such as the liver or gut, given that they present 24-hour rhythms in many of its functions. Animals with mutated circadian clock genes such as Bmal1, Per1 and Per2 are known to develop tumor processes more frequently as they act as tumor suppressors.

light at the end of the tunnel

Examining the role of chrono-disruption and the shifting of our synchronization with the light and dark cycles could lead to an advance in knowledge of diseases such as cancer.

We are an ecosystem close to the environment, and light, in a perfect biological promise, acts as a cog, limiting the activity of our central and peripheral clocks to the rhythmic beat of the same beat.

Light guides, coordinates us like musicians, painters and philosophers, shaping us inexorably clockwise in this life, inexorably.

This article is the winner of the 2nd edition of the youth information contest organized by the Lilly Foundation and The Conversation Spain.

Claudia García Cobarro, PhD student and researcher in the Physiology, Nutrition and Chronobiology group, University of Murcia

This article was originally published on The Conversation. Read the original.