Ashwagandha
Shop on AmazonA commonly used adaptogenic supplement taken to help lower cortisol and blunt stress reactivity. The dominant guidance is to use it in short bursts rather than continuously, with one recommendation warning against chronic use beyond about two weeks of regular dosing. Its appeal is that it may act as a fairly potent cortisol reducer, though the evidence base is still limited.
“If you're going to experiment with ashwagandha as a means to reduce your cortisol levels... dosages somewhere between 300 milligrams... all the way up to 900 milligrams. But typically I would recommend... somewhere in the neighborhood of 300 milligrams, at least to start... that you restrict your intake of ashwagandha to the late afternoon and evening and nighttime hours.”