Caffeine is a stimulant which is found in coffee, tea, fizzy drinks, energy drinks, painkillers, headache tablets and Pro-plus.
Taken in small quantities it can improve concentration and make you feel more alert for longer.
Too much caffeine, however, can produce similar sensations to those of anxiety including faster breathing, headaches, increased heart rate and irritability.
Aim to drink no more than two cups of coffee (fresh coffee is higher in caffeine) or four cups of tea a day.
If you cut down your intake suddenly you can experience the effects of withdrawal including headaches, tiredness or feeling anxious or sick. If you need to reduce the amount of caffeine in your diet – do it slowly. Try changing to decaffeinated tea and coffee, herbal tea or water.