Ideally, you will want to find a supplement which contains a moderate caffeine dose. (fitnessandpower.com)
«Repeated caffeine doses increased cortisol levels across the test day without regard to the sex of the subject or type of stressor employed». (supernaturalacnetreatment.com)
In rats, theanine administered intravenously after caffeine dosing, and at approximately the same dose, blunted the stimulant effect of caffeine seen on electroencephalographic recordings. (chiro.org)