For Calm Energy and Focus. Source Naturals Caffeine + L-Theanine delivers the energy benefits of caffeine with the calming benefits of L-theanine, to help you start the day focused and productive. In contrast to the nervousness that can come from consuming excess caffeine by itself, these two ingredients work together to provide calm, focused energy. Clinical research has shown that caffeine and L-theanine have a synergistic effect on attention and accuracy, and together support healthy focus and memory better than the use of each ingredient by itself. We suggest you start with one tablet but increase to two if the desired effect is not achieved.