Mental stimulants can obviously stimulate thinking in bursts. Tea and coffee, both based on caffeine, are the world’s leading mental stimulants. Tea is extremely healthy. Coffee is a mixed bag – very healthy in some regards, but also a little unhealthy because of its adrenal-draining action. Dragon herbs offers these two herbs. Here are some Dragon Herbs products that support powerful thinking. Tea also contains an amino acid known as L-Theanine that is relaxing but mentally focusing.