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The Bad and the Good - Caffeine


My love for caffeinated drink (specifically coffee) started after university when I discovered its amazing effects on my cognition (it allowed me to not only stay awake, but REALLY awake, it felt like my brain was running on steroids). After decades, my love for it still remains, but I've learned to tinker with it according to:


1. My energy level (basically how I feel cognitively and physically)

2. My diet

3. My sleep quality from the previous night

4. My plans for the day


To say that I've completely grasped the effects of caffeine is a complete lie, I also question those who claim they have unlocked the perfect dose for caffeine ingestion, or perfect dose for any chemicals for that matter. However, I think there are things about caffeine that most people don't understand, and I hope I can shed some light on that.


Bad News?

Let's start with the bad, since most of the social media information about caffeine these days are negative (for good reasons, because I do think people are drinking coffee under the wrong circumstances..). To understand why caffeine may be affecting your health in a negative way, we'll look at 2 popular effects it has on the body:


1. How it keeps us awake

2. How it affects our stress hormone


How does caffeine keep us awake?

To understand how caffeine keeps us awake, we have to look at the chemical adenosine. Many people have heard of ATP (adenosine triphosphate), and understand that ATP is an energy currency in our body that allows us to move, talk, think, eat, digest, etc.. It basically is the currency in our body that keeps our cells running and thus, keeps us alive. As we go on about our regular day, we also expend more and more ATP, which through a complicated process, can eventually breakdown into adenosine (energy is created by the cleavage of phosphate groups).


Adenosine can have multiple different effects depending on the type of receptor it attaches to, but one of the global effects of having too much adenosine build up in the brain is that it creates sleepiness (it builds your sleep pressure). Adenosine is usually cleared and recycled during sleep by the cerebral spinal fluid, that is why if you do not have adequate sleep, your sleep pressure can be tremendously high and cause you to fall asleep behind the wheel (really... really bad). So what does caffeine have to do with all this adenosine talk? Well, caffeine is extremely similar in its chemical structure to adenosine, and competes with adenosine receptors (think of adenosine and caffeine playing musical chair..), but it doesn't activate the receptor it binds to (in science that is called an antagonist). So a typical receptor that is bound to adenosine will create sleepiness, and when caffeine wins the race to the chair, it just sits there can like a rebellious kid, not accepting any responsibilities (which by the way is also why most people may "crash" once caffeine wears out in your system, because now adenosine, like a responsible adult, will not stop until it bind and activate all its receptors).


So why is this bad? It is still unclear as to the exact long-term effects of caffeine will do to these receptors, but from what we understand about the body is that it is an extremely smart system. An increase in demand leads to an increase in supply, meaning more caffeine, more adenosine receptor. Our body starts to create more and more receptors to meet the demand. That means more chairs available for adenosine to sit on, and you will need to drink a heck of alot more caffeine in order to block that adenosine from binding to its receptor. This becomes detrimental because of 2 reasons (that I've figured out anyway...i'm sure there are more reasons):


1. It will affect your ability to fall asleep when you need to

2. Increased caffeine means more adenosine build up in the brain, and more clearance required by the cerebral spinal fluid


Essentially, it becomes a vicious cycle of: feeling sleepy --> coffee --> still not quite awake --> more coffee --> finally feeling a little more awake --> but its 6pm --> having a hard time falling asleep OR/AND falling asleep fine but brain is busy clearing adenosine instead of doing all its other wonderful stuff --> waking up feeling sleepy because there are still adenosine present.


How does caffeine affect our stress hormone?

Stress is crucial in allowing you to become stronger, physically, mentally, and immunologically (not sure if that's even a word). Our nervous system can be generalized into 2 different categories: sympathetic nervous system (fight or flight) and the parasympathetic nervous system (sleep and digest). The reason stress is important is because it activates our sympathetic nervous system, which allows us to become vigilant, increase heart rate and blood pressure, and free up stored glucose so we are readily able to contract our muscles when required.


Caffeine can readily activate the HPA-axis (hypothalamic-pituitary-adrenal axis) which results in an increase in adrenaline and cortisol, which is responsible for everything that is mentioned above. Most people have heard of cortisol, and it's gotten quite a negative connotation to it, but it's not all bad. In fact, in a healthy body, our cortisol level goes through a circadian rhythm, where it goes on a steady rise the minute we wake up (or even before we wake up) and peaks around 1-2 hours after awakening (reasons are not clear, but speculation is on our ability to be vigilant for the start of the day, and to better cope with the our perception of the world. I mean..makes sense given that we used to need to fend ourselves from lions and tigers the minute we wake up, not to mention snakes, scorpions, spiders...).