Green tea has an ingredient that actually counteracts the caffeine it contains. The amino acid theanine, found in green tea, has been shown to reduce mental and physical stress, improve cognition and mood and has a relaxing effect when consumed. Theanine is even used as a natural calming agent for its ability to cause states of relaxation without sedation. So green tea, despite its caffeine, has an overall calming effect. Most people find they can drink green tea late at night and it won’t keep them awake.
—Coffee vs. Green Tea: Both Have Caffeine, But One is Healthier – thatsfit.ca As someone with an acute sensitivity to caffeine, I’ve noticed that green tea doesn’t bother me. Now I know why.

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