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Effects Of Caffeine

How caffeine effects sleep and the brain

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How caffeine works

Caffeine is often consumed through coffee, tea, soft drinks and sweet treats.

It is a competitor of the sleep-promoting chemical adenosine.

By competitor, I mean it is attracted to the same receptors in the brain as adenosine.

When caffeine binds to these receptors, adenosine cannot, and visa-versa; when adenosine binds to these receptors, caffeine cannot.

Although caffeine is similar to adenosine, when it binds to receptors in the brain, it does not induce the sleep promoting feelings that adenosine does.

Think of an army of Mr Lazys (adenosine) fighting for the same strongholds as an army of Mr Happys (caffeine). They’re similar (both Mr Men), but if Mr Lazy takes over the strongholds, you start feeling tired, if Mr Happy starts taking over, you feel more energetic.

In essence, caffeine occupies brain receptors, leaving fewer available for adenosine to bind to; thus, neural activity is NOT slowed by the effects of adenosine, making you more alert.

Cup of coffee

Caffeine’s battle with adenosine also impacts upon the amount of dopamine, the feel-good neurotransmitter, that is released in the brain.

This is because adenosine molecules close the gap in certain brain receptors that accept dopamine, stifling feelings of happiness.

Again, caffeine competes with adenosine for such positions but, unlike adenosine, caffeine does not block dopamine, meaning the “happy-hormone” is free to lift your mood (which can cause addiction).

By operating in this way, some studies suggest that caffeine can reduce the risk of diseases such as Parkinson’s, Alzheimer’s and certain types of cancer.

On the flip side, it is also suggested that caffeine can increase your heart rate, blood pressure and lead to insomnia and anxiety.

How long does caffeine last?

Caffeine is broken down relatively quickly – two to four hours depending on genetics.

The build-up of adenosine does not stop just because you ingest caffeine; therefore, you can feel a sudden “crash” as the neurological floodgates open, allowing adenosine in!

If you ever feel tired a few hours after a coffee, that’s why. It’s because, as caffeine wears off, more brain receptors become available for sleep-promoting adenosine to take over.

Side effects of too much caffeine

After a prolonged period of regular caffeine consumption, your brain naturally develops more receptors to cater for both caffeine and adenosine.

This is why you can become caffeine tolerant.

It is also the reason sleep seems to intensify for people who stop taking caffeine after a prolonged period of regular consumption.

Caffeine withdrawal

According to scientific research, the symptoms of caffeine withdrawal begin one or two days after you stop consuming it and consist mainly of headaches, nausea and sleepiness.

Caffeine before bed

Caffeine not only keeps you alert and awake, it can also impact on the depth of your deep sleep.

Even if your last cup of coffee was at dinner time and you fall asleep fine, it can still impair the depth of your deep sleep!

Lighter sleep means you feel less refreshed after waking, even if you feel like you slept fine and didn’t wake up throughout the night. You know what I mean… the “I slept fine but feel a little groggy” feeling.

This often leads to a dependency on a morning caffeine fix. Again, you know what I mean… how much do you hear the common phrase “I can’t go without my morning tea/coffee.”

This is the start of an addiction cycle.

Coffee nap

It may seem counter-intuitive to drink coffee before a nap, but you do hear people endorsing this “energy hack.”

A coffee nap is the title given to a procedure where you quickly drink a cup of coffee, immediately before you take a 15 to 20 minute nap, leading to a double whammy of increased alertness.

Coffee nap

Firstly, you metabolise (break-down) adenosine during the nap and secondly, caffeine has enough time to enter your brain where it has less competition from adenosine.

More caffeine molecules will then be able to bond with receptors just as you wake up, leaving you feeling mentally sharp and refreshed.

Though the logic seems reasonable, it is difficult to find scientific studies that prove a coffee nap is more beneficial than just a nap, or cup of coffee on its own.

How do you use caffeine?

Studies show that caffeine can have both positive and negative effects.

As with anything in life, the trick is to understand how your body reacts to caffeine and make smart, informed choices to fulfil your goals.

This article provides a helpful outline of caffeine levels in common products


Let us know your views on caffeine. Do you use it or do you avoid it?

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