WION Decodes | Why does coffee calm some people instead of waking them up? Here’s what science says

Does coffee make you feel calm or sleepy? You are not alone. While many people feel a burst of energy after drinking coffee and other caffeinated drinks, it is not the case with everyone. Coffee may have a completely opposite reaction for some people, who may feel calm, relaxed, or even sleepy. While this may sound absurd to many, science reveals that it is actually quite possible. In fact, there are several biological explanations for how caffeinated drinks affect individuals differently.

The biggest myth about coffee

One of the biggest myths about coffee is that it gives a person energy. In reality, caffeine works by blocking a brain chemical, adenosine, which builds up in the brain during the day and produces an effect of tiredness. Caffeine affects the body and brain in such a way that it blocks the receptors for adenosine and prevents sending signals of fatigue to the brain. This provides an effect of increased energy by covering the feelings of tiredness.

Caffeine rebound effect

The next question arises about what happens to the adenosine when it is blocked by caffeine. Even when caffeine is blocking the adenosine receptors, the body continues producing it. Soon, when the effect wears off, the accumulated adenosine gets attached to its receptors. This phenomenon, often referred to as an adenosine rebound, can cause fatigue and sluggishness. For some people, especially those who are already sleep-deprived, the rebound effect may happen relatively quickly, making it seem as though coffee itself caused drowsiness.

Can genes determine how coffee affects you?

Absolutely, yes. Your genes can have an impact on the caffeine sensitivity of your body as they can determine the metabolic rate of caffeine in your body and its response from the brain.

One such important gene is CYP1A2, which impacts the metabolism of caffeine in the liver. For individuals who metabolise caffeine faster, the effects would last for a much shorter period of time, and they would feel drowsy very soon. On the other hand, for individuals who metabolise it slowly, the effect may remain for much longer.

Another gene, ADORA2A, affects adenosine receptors that determine the sensitivity of an individual to caffeine. The differences in these genes could have a major influence on how one feels after consuming coffee.

Why coffee can feel calming

Coffee can also indirectly influence dopamine, a neurotransmitter that regulates attention, motivation, and reward behaviours. In some individuals, especially those who have issues with being distracted or mentally overstimulated, caffeine intake can boost concentration and help declutter the brain. In this case, caffeine can help individuals feel more focused and calm rather than making them excited or jittery. Coffee does not make people sleepier, but it can increase the brain efficiency levels.

Caffeine and ADHD

The scientific community has already observed how individuals with Attention Deficit Hyperactivity Disorder (ADHD) react differently to caffeine. Even though caffeine is not used in medical treatments for ADHD, it can influence the pathways regulated by dopamine.

Caffeine can having a calming effect for majority of people with ADHD and also improve their concentration. Some may also feel drowsy after caffeine consumption. Despite the unclear reasons why stimulants have a relaxing effect on individuals with ADHD, such a phenomenon was also observed among prescribed stimulant drugs.

Caffeine tolerance

Your response to coffee may also depend on your caffeine tolerance levels. People who consume coffee on a regular basis experience less stimulating effects compared to infrequent consumers. This is because over time, the brain adapts to repeated caffeine exposure by adjusting its adenosine system. Consequently, a morning cup of coffee won’t have the ability to energise and stimulate you anymore, but will simply return your body to the average level of alertness.

The bottom line

One of the largest myths associated with caffeine is the notion that everyone should be able to stay awake after consuming coffee. Coffee is known to help people to become more alert; however, there is no predictability in its effects. While some people are energised after drinking coffee, others are calmer and more concentrated, yet there are those who want to fall asleep instead.

Thus, feeling unusually relaxed or sleepy after drinking coffee does not mean that caffeine doesn’t have the desired effects. It might actually indicate something about how your body and mind react to caffeine.

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