Caffeine sensitivity refers to how individuals react to caffeine, a stimulant found in coffee, tea, chocolate, and some medications. People with high sensitivity may experience stronger effects from smaller amounts of caffeine, such as increased heart rate, anxiety, or insomnia, while those with low sensitivity may tolerate larger doses without noticeable side effects. Genetics plays a significant role in caffeine sensitivity. Variations in genes, such as the CYP1A2 gene, influence how quickly caffeine is metabolized in the body. This means that some people can enjoy their favorite caffeinated beverages without issues, while others may need to limit their intake to avoid discomfort.