Some people can drink more cups a day without feeling the stimulating effect of caffeine. Here because
We drink it because it is good, but also because we need a boost of energy. Coffee is also famous for this: the caffeine it contains, the most consumed stimulant in the world, helps us keep our attention alive and increase efficiency. But it doesn’t work for everyone: some people, for example, can drink more cups during the day and feel virtually no effect. Others may even feel more tired after their espresso.
Here because. Adenosine is a chemical in the brain that influences the sleep-wake cycle: its levels increase during waking hours and decrease while sleeping. Normally, adenosine molecules bind to special receptors in the brain, which slow down brain activity in preparation for sleep. But caffeine, by binding to adenosine receptors, prevents this from happening.
When the coffee does not give (more) the charge
The body absorbs caffeine rather quickly (99% within 45 minutes of consumption): people can feel the effects even in a few minutes. But once the body metabolizes it completely, its effects vanish. The permanence of caffeine in the body varies from person to person: the speed with which it is metabolized varies according to genetic factors and lifestyle.
But people who regularly consume coffee (and other drinks that contain caffeine) can develop a tolerance to the stimulant effects of caffeine, which means they have to drink more if they want to experience similar results. And, although caffeine blocks adenosine receptors, it does not affect the production of new molecules of this substance: when it fades, the adenosine molecules can return to bind to their receptors, and the consequence is a feeling of drowsiness.
In one study, researchers examined the effects of continuous caffeine consumption on the cycling performance of 11 adults. At the beginning of the experiment, the participants had higher heart rates and had more momentum after drinking caffeine. But 15 days were enough for the effects of caffeine to begin to decline.
At this point, to go back to feeling the energizing effects of coffee, all that remains is to drink a little more, but without exaggerating: the Ministry of Health, based on Efsa data, suggests to the adult a consumption of up to 200 mg of caffeine per day (although up to 400 mg per day there should be no health problems in healthy adults). Normally an espresso coffee does not exceed 80 mg of caffeine, while an American coffee, long and in a large cup, can reach 90: at the fifth cup, it is good to stop. And if even then you still feel underwhelmed, maybe it’s a sign that you need a vacation.