Coffee is a magical drink that can make a busy person’s morning. Coffee’s stimulant effect is due to the substance called caffeine. Caffeine can make the mind more alert and drives away sleepiness for about 3~4 hours. This is why students studying for an exam or people working late love to drink coffee.
There are many students who say they do not like coffee and drink energy drinks instead. These drinks tend to advertise that the substances guarana and taurine give energy, but an interesting fact is that guarana is just a plant where caffeine is extracted from. Taurine has many beneficial actions in the body, but has no effect as a stimulant. Therefore, an energy drink is simply made of caffeine and sugar and holds no advantage over coffee.
Although caffeine is beneficial in moderate amounts, excessive consumption leads to adverse effects. A normal adult can handle up to about 400mg of caffeine. Any more and they could suffer from anxiety, insomnia, headaches, dehydration, increased urination, fever, rising heart rate, stomach pain, nausea and many other symptoms. As everyone’s rate of caffeine metabolism is different, only they know how much caffeine they can consume. Furthermore, the more coffee or tea you drink, you build a tolerance towards caffeine and can consume much more without adverse effects.
The following is a list of the caffeine content in common drinks and foods:
- Drip coffee(200ml): 150mg
- Espresso(50ml): 100mg (this is because the cups are small, the concentration is about 3 times that of drip coffee)
- Caffeine tablet: 100mg
- Energy drink(250ml): 80mg
- Coca-cola(600ml): 60mg
- Chocolate(250g): 60mg
- Black tea(170ml): 50mg
- Green tea(170ml): 30mg
- Decaffeinated coffee(200ml): 10mg
However, the best method to drive away sleepiness is by sleeping. If you are tired, the only way to recover is by taking a 30 minute to 2 hour nap, especially if you will be driving or have a night shift.