<human>:  What are the effects of drinking caffeine?
<bot>: The effects of drinking caffeine can vary greatly depending on the person, the amount consumed, and the frequency of consumption. Generally, caffeine is a stimulant, so it can increase alertness, focus and concentration, as well as physical and cognitive performance. It can also increase heart rate, blood pressure and cause restlessness, nervousness and headaches. Caffeine can also lead to sleep disturbances, increased anxiety, increased irritability, and in some cases, addiction and dependence.