Chocolate is lower in caffeine than tea, coffee and coca cola. A one ounce bar of chocolate contains about 6mg of caffeine, whereas a five ounce cup of regular coffee contains over 40mg.
It has been shown that caffeine causes headaches when stopped suddenly and can cause morning headaches that are relieved by a dose of caffeine.
Englishmen drink more tea than any person of any other nation (over twenty times more than Americans)
You can overdose on caffeine.