Many people describe their desire to eat chocolate as a craving and they also report that eating chocolate relieves tension. How this happens is still not fully understood and it is still being researched. One of these chemicals is called serotonin and it is thought to relax and calm people. One theory suggests that a decrease in serotonin in the brain leads to a craving for starches and sweet foods like chocolate. When serotonin levels rise again a feeling of well being is said to return.
Endorphins are another of the chemicals which are thought to produce the feel good factor.
Endorphin levels seem to be controlled by dietary fat and it has been suggested that eating fat containing foods like chocolate might improve one's mood by increasing the levels of endorphins. Another suggestion is that craving for chocolate is related to psychoactive ingredients. Chocolate does contain theobromine but this is a relatively weak central nervous system stimulant which does not have strong subjective effects. Chocolate also contains caffeine but compared with tea and coffee it is an insignificant dietary source. Attitude to food may also be a factor in describing the desire to eat food as a craving.