AND YOU Consider the popularity of Tea houses in China, the Japanese Tea ceremony, British afternoon tea, and of course, morning coffee in the United States. All of these rituals involve caffeine.
Caffeine is a stimulant that affects many parts of the body.
Let's talk about the brain first. Higher doses of caffeine may cause insomnia, nervousness, restlessness, and even mild delirium. This dilation of blood vessels also causes increased blood flow to the kidneys which may explain another effect of caffeine, increased urination. Finally caffeine also affects the muscles of the body by increasing the force of contraction and decreasing fatigue. First of all, studies have shown that caffeine does increase motor activity.