Does ltheanine reduce stress?

No: Theanine can relax you when stressed, but it does not reduce the stress itself. What you perceive as "stress" is unique to each person, and a more lasting solution is to work with a therapist about it. Then you can understand more about your makeup, and learn to handle what comes with more balance. Seeing things as threatening is stressful for most of us -- but therapy can improve resilience.