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Caffeine Part 2: How Caffeine Works?

Caffeine is undeniably one of the world’s most widely consumed stimulants. We consume it… We love it… but have you ever thought just how caffeine gives you energy? Well, we’re going to take you through the basics of how caffeine really works in the body so that you are able to make the most out of your caffeinated beverage. However, before we jump in, it’s important to first understand the basis of a powerful little chemical in the brain called adenosine.


Adenosine is an extremely important molecule naturally present within every cell in the body. It’s found all throughout the body from the heart to the brain and it holds a wide range of functions. One function you may be familiar with is cellular energy. Adenosine is the building block of adenosine triphosphate (ATP), which is used in cellular energy, such as to help your body move and muscles to contract. However, adenosine works a bit differently in the brain. It plays an opposite role of energy and instead a key part in regulating sleep.

Adenosine is considered a chemical messenger otherwise known as a neurotransmitter. The purpose of neurotransmitters are to help send chemical messages to different neurons in the central nervous system. They work very similarly to a lock-and-key system where the neurotransmitter adenosine acts like a key and an adenosine nerve cell has a receptor site, which acts like a lock. Adenosine can bind to adenosine receptors and unlock a message to slow neural activity and make you feel tired before bed. Generally, the higher the concentration of adenosine the more tired and relaxed you become.


That’s where caffeine comes in. Once consumed, caffeine is digested and absorbed in the gut and able to cross into the brain. Once caffeine reaches the brain, it then has the ability to intercept adenosine from acting in the brain, because it has a near identical chemical structure to adenosine. Due to the molecular similarities, caffeine can actually bind to the exact same receptors as adenosine. Meaning caffeine competes with adenosine once it enters the brain. Both molecules essentially have to fight to bind to the same receptors. Despite caffeine’s able to fend off adenosine and bind to the same nerve cells – it does not have the ability to unlock the cell. Instead caffeine just deflects adenosine from slowing neural activity and sending messages of tiredness.

Once caffeine is bound to the nerve cell it can then trigger other neural circuits in the body to react. First, it can stimulate the adrenal glands to produce adrenaline, the body’s ‘fight or flight’ hormone, which helps to promote alertness and wakefulness. Secondly, it can stimulate the brain to produce dopamine, a neurotransmitter involved in concentration, which helps to support focus and attention. The time at which caffeine may be realized takes time. In fact, it can take anywhere from one to two hours after ingested for caffeine to peak. Caffeine is not stored in the body. The body can break it down in about four to six hours at which time the effects of caffeine begin to dissipate and it gets expelled. The way in which your body responds to caffeine depends on you and much much more.


The body’s sleep-wake cycle is dependent on a multitude of factors from our body’s circadian rhythm, levels of melatonin and more. This is the interaction shown above is simply the interaction between adenosine and caffeine. The overall process if fairly complex, therefore it’s important to remember the big picture. Everyone is unique and how their bodies metabolize caffeine will differ. Meaning each person responds differently to caffeine. Know your tolerance to caffeine and find what works best for you. Aside from one of our beloved caffeine, remember to prioritize quality nutrition and sleep each day. Plan caffeine intakes accordingly and find a routine that is sensible and includes balance and moderation.