The Science of Caffeine

Ever wondered what the magic ingredient in your coffee is that can jolt you back to life? The little miracle that keeps you awake in lectures, or fuels your late night.

That’s exactly the question I was pondering, as I made my daily commute into university. What is in this disposable, paper cup that is so indispensable? 

The all important disposable coffee cup.
The all important disposable coffee cup. Image: Wan Mohd, Source

Caffeine. I’m sure this is no surprise to you. We’ve all heard about this little treasure. In fact, it’s the world’s most widely consumed legal drug. First discovered in the 9th century, coffee has become an integral part of the modern Western lifestyle. But how does it work?

How does caffeine work?

As it turns out, caffeine is nothing but a biological doppelgänger. It’s the same shape and size as a neurochemical found in our bodies called adenosine.

Normally as your neurons fire throughout the day adenosine builds up in your body. This is because your body breaks down glucose to produce a molecule known as ATP. ATP is the energy currency of life, and it is used to fuel lots of processes. So as you go through the day, you use up lots of this ATP (or energy), leaving behind adenosine in the process.  The nervous system has special receptors that can monitor the adenosine levels in your body. When adenosine binds to these receptors, it slows down nerve cell activity – this is what makes you feel drowsy or tired towards the end of the day.

Caffeine looks a lot like adenosine, and can bind to the receptor instead. Much like a bouncer, it prevents adenosine from passing through the receptor and getting access to the party. This means that adenosine molecules can’t enter, preventing you from getting tired. Miracle!

Caffeine Blocking Receptor
Caffeine prevents adenosine molecules from passing through the adenosine receptor, so they build-up outside. Illustration by Yasmin of “Weird and Wonderful Science”.

But there’s more to it. Caffeine not only keeps you from getting tired, but it also gives you a boost of energy – a coffee kick. With adenosine receptors clogged, neurotransmitters like dopamine and glutamate cause increased neuron firing, making you feel more alert and awake. The pituitary gland, a small pea-sized structure found at the base of your brain, detects this change and responds by releasing molecules that tell your body to produce the “fight or flight” hormone, adrenaline. This is why after a cup of Joe, your heart rate increases and you feel excited.

Unfortunately, the effects are short-lived. Enter the coffee crash. It happens to the best of us. You’re tired and have work to do, so you glug down that much needed coffee and get the energy boost you need. Then a few hours later, it all goes downhill. You start feeling increasingly tired and cranky, and you struggle to concentrate. This is because the caffeine in your body is being metabolised, and is no longer blocking entry of the adenosine molecules. The bouncer has gone home after a hard day’s work. The build-up of adenosine can then rush through your receptors, and signal to the body that it’s time to sleep, but at a level that’s much more intense than normal. The result is that you end up feeling even groggier than you did before.

Caffeine Hangover
The caffeine crash makes you feel more tired than you were before. Image: Michael Frank Franz, Source

Is the caffeine hangover avoidable?

According to caffeine-informer it is, so long as you follow these key steps:

  1. Make sure you’re well rested. If you start off the day with the correct adenosine levels, it may help prevent a caffeine crash.
  2. Spread out your caffeine consumption throughout the day. Don’t have 2 big cups of coffee in the morning. Instead have one in the morning and one in the afternoon.
  3. Keep your caffeine dose within reason. For healthy adults with no medical issues, it’s thought that 300-400 mg of caffeine can be consumed daily without any adverse effects. One grande coffee from Starbucks contains 330 mg of caffeine. Remember, all of this caffeine should not be consumed in one go (Step 2).
  4. Don’t consume caffeine on an empty stomach. Caffeine might be a quick fix, but food is what actually provides the real energy for your body. If you haven’t eaten, once the caffeine wears off you’ll be left feeling tired and fatigued.

The caffeine hangover can be avoided by taking caffeine in moderation as part of a healthy diet and lifestyle. In fact, caffeine is actually thought to have some health benefits.

Caffeine – friend or foe?

In a study at Harvard, it was found that moderate coffee consumption was associated with reduced risk of death from cardiovascular disease, diabetes, neurological diseases such as Parkinson’s disease, and suicide.

Some of these findings may be to do with the other beneficial properties of the coffee bean, but most can be linked to caffeine directly.

So next time you’re having a morning cup of Joe, or a red bull fuelled Jaeger-bomb, you’ll know exactly how it’s keeping you awake.

Header image: pixabay, Source
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