Caffeine, mighty caffeine. CNS(central nervous system) and metabolic stimulant, nootropic, and the world's most widely used psychoactive compound. It makes us feel great, but why?
Its main mechanism of action is the blocking of Adenosine, a nucleoside with a generally sedating and relaxing effect, the absence of which results in an added alertness and vigilance, which also can be attributed to its modulating effect on adrenaline/noradrenaline levels, as well as most other prime neurotransmissions.
Aside from its well-known mental effects regarding concentration and focus, larger doses(400mg+) have been seen to noticeably improve physical strength and endurance.
L-Theanine is an amino acid analogue of the protoinogenic(protein precursor) amino acids L-glutamate and L-glutamine, which was first discovered as a constituent of green tea prepared from Camellia Sinensis in 1949.
It has been seen to promote alpha brain waves, which are prevalent during the "relaxed mental state, where the user is at rest with eyes closed, but is not tired or asleep", such as when one performs meditation. It has been widely used in conjunction with caffeine to augment its negative effects, such as caffeine jitters or the scattering of ones thoughts.
There are an increasing number of studies that suggest L-Theanine may be effectively used to modulate a variety of stims, not solely caffeine, and it has been seen to increase the disease-fighting capacity of gamma delta T cells, boosting the immune system overall.