What Does Caffeine Really Do to Your Body?

Generally most of us consider drugs to be a bad thing and yet we use a number of them on a daily basis, often without giving it a second thought. Everyone else does it, so why should we worry? As long as it’s socially acceptable and normal, we don’t need to really think about what’s actually happening in our brains, right? One of the most socially acceptable and most popular of these is of course caffeine, which we don’t only enjoy regularly, but even rely on at times to perform our daily tasks.

Caffeine is a stimulant in a similar way to amphetamines, meaning that it excites the body and increases our alertness rather than suppressing it and dulling our senses like a depressant (alcohol being the prime example). Unlike amphetamines however, caffeine has very few negative side-effects and has only a relatively mild impact on our bodies. But do we really know what it does to us? And how it affects our brains – permanently in some cases – and even our personalities? Read on to find out…

The Mechanisms of Caffeine

Caffeine has a number of impacts on the brain, not only increasing the production of dopamine and adrenaline (to an extent – resulting in the bobbing legs and fluttering heart), but also blocking our ‘adenosine receptors’. Adenosine is a substance that build up in the brain throughout the day and ultimately makes us feel tired and lethargic when it interacts with our adenosine receptors, but by using caffeine we are able to block our intake of that adenosine (the caffeine acts like a ‘plug’) and thus prevent that effect temporarily. After 4-5 cups of coffee we block around half of our adenosine receptors and this can make us more alert, more switched on and more able to handle multiple tasks.

This understanding of caffeine’s interaction with the brain is relatively new, and it sheds an interesting light on what the effects of caffeine over long periods might be. If you block your adenosine receptors regularly for instance, then it can affect the sensitivity and availability of those receptors. Interestingly, this could help to reduce dementia and a number of other degenerative brain diseases (something which research has suggested in the past).

And we’ve all heard by now that as an antioxidant, caffeine can also protect against cancer. So it’s looking pretty good for coffee drinkers…

Then again though, the fact that we can build up a ‘tolerance’ to caffeine (as with most drugs) over time is worrying, as it suggests that we might become more sensitive to adenosine over time – potentially making us more tired when we’re not on caffeine. The long-term effects of caffeine are still not fully known, but other changes include an increase in norepinephrine receptors (which might make us calmer) and serotonin (a happiness hormone), versus an increase up to 65% in GABA receptors. GABA does a number of things, including helping to regulate muscle tone, control the firing of neurons and manage sleep. Whatever the end result of all these changes, they tend to take around a week to 12 days to kick in – so you develop that tolerance very quickly.

Another issue to consider is withdrawal – and this is something that most people will experience 12-24 hours after ceasing regular use. Apparently this is why so many people experience headaches when they come out of an operation: it’s not to do with the anaesthetic, it’s to do with caffeine withdrawal! If you can put up with it for around 10 days though, you’ll find that you quickly recover.

Personality Changes

Caffeine can also temporarily result in personality changes. As well as headaches for instance, common side effects of caffeine withdrawal include depression, fatigue, nausea and irritability – part of the reason many of us are grumpy before our first cup of coffee.

And while you’re on caffeine you’ll find that your personality can change slightly too – particularly if you have a lot or you’re very sensitive to it. Specifically this is likely to result in increased anxiety, paranoia and fear, which is likely to do with the increase in adrenaline – which is after all the ‘fight or flight’ hormone – and cortisol which is the ‘stress hormone’ (though this is working against increased levels of serotonin and dopamine…).

While most people won’t notice these changes to a large degree, if you’re someone who is naturally ‘panicky’ and excitable, then you may be better off avoiding getting too much caffeine.

Physical Changes

It’s not just your brain that’s affected by caffeine either. Because caffeine makes us produce more adrenaline for instance, our hearts beat faster and our metabolisms speed up and this can then cause us to burn more calories and fat – making caffeine a mild ‘thermogenic’ that can be used for weight loss. On the other hand though, the fact that it also causes us to produce cortisol – which can weaken muscle tone and cause us to gain weight – means that these effects might be mitigated.

Another point to bear in mind is that caffeine can potentially cause us to lose some of our fine motor control as it causes ‘shakes’ in those who are particularly affected by it. If you drink a lot of coffee in one go or are sensitive to it, then this won’t help you to put play Operation.

Does it Make You Smarter?

So using coffee and tea will help you to feel more awake, principally by removing one of the signals that tells our brain it should be tired. But how does this impact on our actual performance? Well as a basic rule, caffeine has been shown to boost speed in particular tasks though not skill – depending on the skill in question.

Creative work, abstract thinking and literature for instance aren’t boosted by caffeine. You might be able to stay awake longer while writing your haiku, and you type more quickly, but the quality of those poems isn’t going to be any better than it would have been without caffeine.

On the other hand, if you’re doing lots of sums, then caffeine may help as it can improve memory. This is particularly true of ‘declarative memory’ – the memory we use to store lists and facts. So caffeine really can help if you’re cramming for an exam…

Interestingly, this memory effect might be caused specifically by the increase in adrenaline – which is also probably why we remember times when we were scared, excited or stressed in more vivid detail.

Individual Differences

Before you get too excited about caffeine though, note that it affects different people differently – depending on your personality and on your biology. Those speed benefits when it comes to working for instance? This is more likely to be pronounced in people who are more impulsive. Why? Because they are generally more happy to ‘go with the flow’ and to sacrifice accuracy for speed.

Likewise, some people are likely to be more affected by caffeine than others depending on a huge number of factors. The average half-life of coffee is about five hours meaning that if you want to sleep soundly you should avoid caffeine 5 hours before bed. Of course if you’re small and light, the effect will be stronger but also faster, and the same goes if you have a faster metabolism. Meanwhile though, women on the pill will take twice as long to process caffeine, and women ovulating will see the same effect. Smokers meanwhile take half the time so they get a much more immediate ‘kick’ from caffeine with a longer ‘come down’. Moreover, some people are just simply ‘more sensitive’ to caffeine than others, perhaps due to their brain chemistry.

So next time you think about putting the kettle on, think about what it really does to you and whether you want to make it a part of your life. On the one hand it may protect you against dementia, and it can help you to work faster and remember more; but on the other it might change your personality for the worse and may lead to withdrawal symptoms. Whatever you decide, our relationship with caffeine is a complex one, and one that we have yet to fully understand…

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