Carolina Escobar Highlights the Importance of Regular Biological Rhythms to Health

For physiologist Carolina Escobar, from the Universidad Nacional Autónoma de Mexico (UNAM), time is ingrained in humans. It is intrinsic to life.

Early on in her conference at the Intercontinental Academia on April 21, she disputed a remark made by physicist Eliezer Rabinovici during his conference on the previous day, that the reaction of prehistoric men to a sunset was panic. Escobar said that biological evolution endowed living beings with an internal clock that allows them to anticipate situations: “When the sun goes down, animals are prepared for it and know how to behave, including how to protect themselves from predators.”

According to Escobar, observing the passage of time does not explain life, because the body changes constantly during the arrow of time (time’s progression toward the future), and is subject to change over the course of its daily cycles – e.g., the phases of the Moon, Earth’s translation around the sun, the differences between daytime and nighttime, variations in temperature, humidity and winds, among other variables.

She exemplified this with the adjustments changes plants and animals undergo each season, mentioning how weight changes in birds depending on migratory needs, the availability of food, reproduction etc. “If animals did not have time within themselves, they would not survive.”

According to her, inhabitants of higher latitudes (temperate zones and polar regions), who are susceptible to significant alterations between seasons, have a higher rate of “winter depression” than those living in the tropics. “Humans do not migrate and they pay a price for it.” She stated that experiments exposing these people to more light show that this helps to abate depression.

Escobar also explained that the hormone melatonin (produced by the body only at night) regulates sleep and plays a key role in brain biochemistry, including the availability of serotonin, the neurotransmitter responsible for wakefulness.

As nights in higher latitudes are longer in wintertime, there is an increased production of melatonin, which reduces biochemical activity associated with alertness and eventually leads to anxiety and depression. The same process also triggers metabolic syndrome, inducing people to gain weight.

Escobar said there are indications that even the phases of the moon – and, thus, the variation of night light –, affect some rhythms of the body, such as the menstrual cycle in women, which according to some evidence tends to synchronize with the 28-day moon cycle.

Escobar believes that some of the main causes of the de-synchronization of biological rhythms in human beings are our excessive nocturnal activity and the fact that we are increasingly less exposed to nature. The consequences, she explained, are gastrointestinal diseases, mental disorders, cancer, stress, lack of concentration, obesity, anxiety and depression. A pernicious loop is thus established: “Diseases change the biological rhythms and the altered rhythms lead to disease.”How regularly the eyes perceive the alternation of light and dark, of day and night, is important for the proper functioning of the brain and other organs. Escobar said that in many older people, who rarely leave home and are therefore exposed to artificial light during the day and part of the night, there are significant changes in the activation of the cycles of sleep and wakefulness. According to her, when exposed to additional lighting during the day, these seniors begin to sleep better and become more active.

The importance of living in consonance with the light/dark cycle of days and nights for our organism’s proper development was demonstrated by an experiment that Escobar’s team carried out in the neonatal intensive care unit of a Mexican hospital. Part of the premature babies had their heads partially covered with a dome during the night, so that their eyes received less light, since the ICU is fully lighted 24/7. Babies who slept under the dome gained weight faster and left the ICU earlier that those who did not.