Coffee: Why are some people more sensitive to caffeine?
Caffeine, the most consumed psychoactive substance in the world, can produce very different effects depending on genetics, metabolism, and the sensitivity of each organism.
While some people need just a sip to perk up, others can drink a double espresso and sleep soundly. This difference in caffeine sensitivity isn't solely due to habit: genetics, metabolism, and how the brain responds to this psychoactive substance all play a role.
The gene that determines how your body processes caffeine
Before coffee takes effect, it undergoes an absorption process into the bloodstream, which quickly transports it to the brain, while the liver breaks it down and eliminates it. The speed at which this detoxification occurs is directly related to your inherited biological makeup. It all comes down to a single gene, known as CYP1A2, which determines how quickly your body processes this chemical.
Dr. Marilyn Cornelis, associate professor of nutrition at Northwestern University in Chicago, explains that it's possible to drink the first cup and feel nothing, but that two or three hours later the caffeine is still present; if you drink another cup, you can reach a point of accumulation that generates anxiety. Furthermore, research shows that genetic predisposition plays a role, making the difference between those who metabolize caffeine quickly and those in whom the substance remains active for hours.
The impact on sleep: how caffeine tricks the brain
At a neurological level, caffeine does not provide real energy, but rather masks tiredness by blocking the action of adenosine, a chemical that accumulates in the brain throughout the day to induce sleep.
Dr. Lindsay Browning, a psychologist and sleep specialist, points out that caffeine not only makes it harder to fall asleep, but also impairs sleep quality. For this reason, specialists often recommend avoiding caffeine at least six hours before bedtime, suggesting as a general guideline that those who sleep at night should stop consuming it after 2 p.m.
External factors and moderation according to experts
Genetics doesn't act alone; various external factors can alter the elimination of the substance. For example, smoking stimulates the liver to process it up to 65% faster, while certain medications, oral contraceptives, and hormonal changes during pregnancy have the opposite effect, prolonging its presence in the body.
Daily consumption decreases brain sensitivity. Given this, experts emphasize that moderation is key, and several long-term studies have shown a positive association between moderation and overall health.
