Does caffeine really make me more alert?

The world's favourite drug

Caffeine is the most commonly used drug in the world with over two billion cups of caffeinated drinks consumed every day.

In Europe, caffeine is mainly supplied by coffee.

About 15 minutes after putting down your cup, you'll begin to feel a caffeine hit that can last hours.

It's a neural jolt some of us rely on to simply think straight in the mornings. And some rely on caffeine's effects to feel mentally agile throughout the day. But how does it work? And does caffeine, in all its forms, really deliver?

How do you feed your habit?

It's a common misconception that caffeine only comes from coffee. In fact it's found in many products. For most people, consuming up to 400mg each day poses no problems. Pregnant women are recommended to drink less than 200mg.

The caffeine content of various products:  cup of filter coffee: 200ml, energy drink: 250ml, espresso: 60ml, cup of tea: 220ml, can of cola: 355ml, bar of plain chocolate: 50g, bar of milk chocolate: 50g.
Serving sizes: cup of filter coffee: 200ml, energy drink: 250ml, espresso: 60ml, cup of tea: 220ml, can of cola: 355ml, bar of plain chocolate: 50g, bar of milk chocolate: 50g.

Stopping the sleepy feeling

Caffeine works by blocking the action of adenosine – a molecule that tells our brain to feel tired.

Faster but not smarter

Scientists have measured the difference caffeine makes to mental performance by testing regular users and non-users. Here's what they discovered from their study:

  • Frequent caffeine users seem more alert, awake and have better attention after they consumed caffeine.

  • However, regardless of caffeine consumption, non-users performed just as well in tests as the frequent users.

  • When non-users consumed caffeine, they felt more awake but jittery. Unfortunately their attention and mental alertness did not improve.

  • Caffeine improved motor skills during 'finger-tapping speed' tests in both frequent caffeine users and non-users.

Caffeine conclusions

While caffeine appears to improve some physical aspects of performance, it does little to enhance the mental abilities of regular users, who quickly develop a tolerance to caffeine’s effects. Non-users meanwhile might feel more alert after a shot of caffeine but they don’t experience any improvement when carrying out mental performance tests either.

Caffeinated beverages
Contrary to popular belief, caffeine consumption appears to have little effect on regular users compared to non-users, when it comes to improving alertness and attention.

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