Neuroadaptation

Neuroadaptation refers to the changes which the brain undergoes to accommodate the presence of a new substance or condition. For instance, drinking a can of coke initially made you feel more awake, however, your system is already used to the caffeine and sugar level which made you more tolerant to the substance. Hence, you now need two cans of coke to feel perked up. This also explains why we are sensitive to something we sense at first but we eventually become used to it over time.