When I was little I had a really bad allergy to caffeine. It stunted my growth, made me moody and affected my motor control. When my parents got it diagnosed when I was six, I grew half a foot, went from being a prime candidate for oral surgery to having a well sized mouth for my teeth, and became a much happier child. The only problem was it was hard to get other parents to understand. Inevitably the first time I went to a friend's house they decided my parents were health freaks and would force me to drink soda or eat something with chocolate and then my parents would get an embarrassed phone call that I was collapsed on the floor crying. It got easier as I got older, because grown-ups started to take me more seriously when I said I couldn't eat something and I gained a higher tolerance. Today I still can't have dark chocolate, coffee or anything caffeine infused without getting an instant and splitting headache, but I quite enjoy milk chocolate and most people's reaction is simply to ask me how I survive without stimulants. The answer of going to bed at a decent hour often seems as alien.