How much caffeine is too much? when would withdrawl symptoms come into effect. what do they look like.

No clear answer: Caffeine withdrawl is familiar to anyone who stops and stays off for a few days. There's a headache, irritability, and tiredness. Sleep may be very deep and pleasant and the dreams vivid. Unlike other drugs, nobody has difficulty withdrawing from caffeine. It's the most popular of all drugs and on the evidence remarkably safe, but use it only to benefit you -- you pay in being more tired later.