L-theanine is best known for relaxed focus: calm without heavy sedation. Many people use it alone for stress response or paired with caffeine for smoother concentration. Purafit rates L-theanine strongest for calm focus and stress support, with sleep benefits depending on timing and individual response. If you’re comparing products, look for a clear per-serving amount and avoid blends that hide theanine behind proprietary focus formulas. Image alt: Purafit ingredient insights panel for L-Theanine with summary, fast facts, and evidence ratings for Calm Focus, Stress Support, and Sleep Support.