How does caffeine keep us awake?
Every year, people around the world consume more than 100,000 metric tons of caffeine. That’s as heavy as about 14 Eiffel Towers! We drink coffee and tea, of course, but so do plenty of other animals. What makes us different is that we put caffeine in our chocolate, our candy, and even our decaf. Caffeine is a good friend, bringing us to life and keeping us aware, but it’s also a cruel taskmaster, keeping us awake and alert when we should be working less and resting more.
Caffeine is like a reliable friend, keeping us awake, focused, and prepared for the day, even when we’re exhausted from not getting enough sleep. But it’s not all good news; having too much caffeine can raise our blood pressure and make us feel jittery.
But don’t worry if you need caffeine to keep you going — it’s the world’s favorite energy boost! So, how does this amazing molecule work its magic to keep us awake?
Caffeine comes from plants, where it plays a few roles. In the right part of the plant, like leaves or seeds, caffeine is an insecticide, lethal to bugs that eat it by the ton, but a treat in the nectar of some flowers, to which it acts as a landing field and a familiar taste.
For humans, caffeine is a booster for our central nervous system. It keeps us awake by getting in the way of the body’s sleep signals in the form of a natural compound called adenosine. Our bodies continually need energy, which they get by breaking down a high-energy molecule called ATP. During this process, adenosine, which is a part of ATP, is released.
Neurons in your brain have special receptors designed to fit adenosine molecules perfectly. When adenosine attaches to these receptors, it starts a series of reactions in your brain that make neurons fire more slowly and reduce the release of important signaling molecules. In simpler terms, this makes you feel sleepy.
Caffeine is what we call an adenosine receptor antagonist. This means it interrupts the process of slowing down your neurons by blocking adenosine receptors. Caffeine and adenosine have similar structures, so caffeine can fit into the adenosine receptors, but it doesn’t activate them because it’s not a perfect match.
In short, adenosine usually slows down your neurons, making you feel sleepy. But caffeine comes in and blocks adenosine, so it actually wakes you up, and it might even boost your mood. Also, some neurons have adenosine receptors that are linked to receptors for dopamine, a neurotransmitter that makes you feel good. When adenosine occupies these receptors, it gets in the way of dopamine’s mood-boosting effects. However, caffeine can take the place of adenosine without affecting dopamine’s function, so dopamine can keep doing its job to make you feel good.
Additionally, studies indicate that caffeine’s impact on adenosine and dopamine receptors could offer long-term benefits, possibly lowering the risk of diseases such as Parkinson’s, Alzheimer’s, and some cancers. Moreover, caffeine may boost the body’s fat-burning capabilities. Interestingly, some sports groups think caffeine gives athletes an unfair edge and have set restrictions on its use.
From 1972 to 2004, Olympic athletes had to keep a certain level of caffeine in their blood to compete. However, not all the effects of caffeine are good. While it can make you more alert and improve your mood, it might also raise your heart rate and blood pressure, cause more frequent urination or diarrhea, and add to problems with sleeping and feeling anxious. Also, foods and drinks with caffeine can affect your body in different ways that need to be thought about.
Regularly consuming caffeine can cause changes in the brain. If caffeine keeps blocking adenosine receptors, the body will make more receptors to make up for it. As a result, even when there’s caffeine in your system, adenosine can still tell the brain to calm down. This might be why people often need more and more caffeine to feel awake, as there are more receptors to block.
Suddenly stopping caffeine can cause uncomfortable withdrawal symptoms. When there are lots of receptors and no caffeine to block them, adenosine can affect the brain freely, leading to headaches, tiredness, and feeling down. But after a few days, the extra adenosine receptors will decrease, and your body will adapt. Eventually, you’ll feel alert again, even without caffeine.
