Have you ever wondered why you feel calmer when you drink a hot green tea? There is a reason to this. Green tea has a very high content of an amino acid called L-theanine. L-Theanine assists with formation of gamma-aminobutyric acid in the brain which is acid blocks that produces serotonin and dopamine. Serotonin and dopamine are known for having a relaxing and calming effects on the nervous system. L-theanine is also knowing for promoting alpha waves in the brain. Our brains produce alpha waves when we are in a relaxed but alert state. Having a alpha wave brain pattern is also known as being in the zone in the athletic field. Many research in this area showed that successful athletes are documented to have higher alpha brain patterns. Alpha waves are also associated with creativity and problem solving. Drugs like Marijuana are also documented to cause alpha brain patterns and this is probably a reason many artists, writers, musicians, etc. smoke pot to get creative.
The good news is that green tea won't give you the jitters since the L-theanine overrides the effects of the caffeine in green tea. It will leave you relaxed and focused. Next time you need to get in the zone, look for a high quality green tea.