The science behind caffeine - how does it get us through the day?
For many of us, the day doesn’t start until we’ve had our morning coffee, tea or energy drink. The magic ingredient in those is caffeine, but what does caffeine do to our brains and bodies that makes it such a popular way to start the day?
What is caffeine?
Caffeine is a naturally occurring stimulant found in coffee beans, tea leaves, cacao pods and more than 60 other plant sources. Chemically, it's known as a methylxanthine and has a structure similar to adenosine, a molecule in your brain that promotes sleep and relaxation.
How does caffeine work?
When you consume caffeine, it travels quickly to your brain and competes with adenosine by binding to the same receptors; however, unlike adenosine, caffeine doesn't make you drowsy, instead it blocks the signal, preventing the brain from getting the ‘time to sleep’ message. This blocking effect leads to an increased activity of neurotransmitters like dopamine and norepinephrine, making you feel more alert and focused.
The Physical Effects
As well as affecting the brain, caffeine also has a range of effects on the body:
Increases heart rate and blood pressure
Boosts metabolism
Enhances physical performance
How Long Does It Last?
Caffeine's half-life (the time it takes for half the dose to be eliminated from your body) is about 3-5 hours. That means if you drink a cup of coffee with 100mg of caffeine at 12pm, about 50mg might still be in your system at 5pm. Some people, depending on genetics and liver function, metabolise caffeine faster or slower, which explains why some can sip espresso before bed with no issue and others can feel the effects from a single cup.
Tolerance and Withdrawal
With regular use, your body adapts by producing more adenosine receptors. That means over time, you may need more caffeine to feel the same effects. If you suddenly stop, those excess receptors can lead to withdrawal symptoms like headaches and fatigue.
How Much Coffee Should I Drink?
Experts recommend up to 400 mg per day for most adults. That’s around 4 brewed cups of coffee.
Caffeine is a powerful ally for boosting alertness, performance, and mood. With a deeper understanding of how it works, you can enjoy your favourite coffee more mindfully.
