Have you ever wondered what is the best time of day to drink coffee? You probably already know that it is not a good idea to take caffeine well in the afternoon, especially if you have trouble falling asleep. However, have you ever had coffee and have had the feeling that it has not had any effect on you? It has happened to me at times. The explanation for this phenomenon is related to a very interesting but little known concept: chronopharmacology.
Chronopharmacology can be defined as the study of the relationship between biorhythms and the effect of drugs. One of the most important biological cycles is known as the circadian rhythm. It is a 24-hour internal clock that marks the physiological behavior and behavior throughout the day, but also the effects of chemicals in our body. The circadian cycle influences how we are affected by drugs (pharmacovigilance), how they move within the body (pharmacokinetics), their efficacy, and even our tolerance to them.
The hypothalamus and the light
What part of the brain is the one that sets the circadian rhythm and in what signals is it based on it? It is considered that one of the main synchronizers (zeitgeber) is light. In chronobiology, a zeitgeber is precisely the environmental stimulus that exerts an influence on the organism’s biological cycles, a spark that comes from the outside, and initiates internal processes within our body.
In mammals light is considered the most powerful synchronizer. After discovering connections between the brain region known as the hypothalamus, and the retina (retinohypothalamic tract), studies point to the hypothalamus as the body’s primary biological clock.
In 1979, researchers Inouye and Kawamura were able to demonstrate this relationship between the hypothalamus and the biological clock. By progressively isolating this region of the brain, the circadian cycle of the organism was completely lost.
What exactly are the functions of this watch? The nucleus of the hypothalamus, a region known as the suprachiasmatic nucleus or SCN, is responsible for controlling sleep and wake cycles, energy and energy consumption, regulation of blood sugar (glucose homeostasis), and production of Hormones among other things. In this sense, the hypothalamus is the regulator of a hormone called cortisol (also called stress hormone) that is critical to alertness.
It is no coincidence that many readers with scientific interest are anxiously awaiting the moment of having their first cup of coffee at breakfast. Several studies and maps suggest that scientific researchers are precisely the part of the population that consumes the most coffee but is it really 8 am the best time to have a coffee? The production of cortisol according to the circadian rhythm suggests no.
The best moment
Tolerance to coffee as a drug is an important point to bear in mind, especially since most of us abuse coffee. It turns out that ingesting caffeine at a time when the concentration of the hormone cortisol in the blood is at its highest point is not the best idea. The reason is that cortisol is directly related to alertness. The peak in cortisol concentration according to the circadian rhythm of 24 hours occurs precisely between 8 and 9 in the morning. It is the moment when the state of alert produced by our own hormones is greater and, if we take caffeine at that time, we simply will not notice its effects.
One of the basic principles of pharmacology is to administer the drugs when they are needed (although I am sure many scientists will argue that caffeine is always needed). Otherwise, we will simply be developing drug tolerance that we manage outside of your ideal schedule. Over time, the 8 o’clock coffee mug will become less effective, and that’s probably the reason I need coffee right now.
Although the high point of cortisol occurs between 8 and 9 o’clock in the morning, later there are other rebounds in the concentration of this hormone in the blood. These secondary peaks usually occur between 12 and 13 noon, and between 17:30 and 18:30. From that point of view, the dose of morning coffee will be more effective between 9:30 and 11:30 in the morning, which will be when cortisol levels are lower.
Another way to stimulate the production of cortisol without having to abuse the coffee is the light itself. The first time I heard about circadian rhythms, my teacher suggested to me that since light is the main synchronizer, one way to stimulate cortisol production to increase alertness would be to drive without sunglasses on the way to the work. Since then I have tried, but the sunlight is too blinding. On cloudy days, however, leaving the house without sunglasses may be of some help.