Complex sentence: Caffeine is a commonplace CNS stimulant drug, occurring both in nature as part of the coffee, tea and yerba mate plants, and as an additive in many consumer products, most notably beverages advertised as energy drinks (such as Red Bull).
Split into simpler sentences: Caffeine is a commonplace CNS stimulant drug which occurs in nature as part of the coffee, tea and yerba mate plants. It is also an additive in many consumer products, most notably beverages advertised as energy drinks (such as Red Bull).