Adaptogens are plant-derived compounds that help the body resist physical, chemical, and biological stressors by acting on the HPA axis and stress-response systems.
Mechanism: Bidirectional. They tend to dampen the stress response when it's excessive and support it when it's depleted. Mechanisms vary by compound (cortisol modulation, HPA receptor sensitivity, neurotransmitter balance).
Use case: Ashwagandha and Rhodiola have the strongest human data. Cycle 8 weeks on, 2 weeks off. Don't stack 5 adaptogens. Single-compound trials are how you know what works for you.
Caveats: 'Adaptogen' is a soft category. Many marketed adaptogens have weak evidence. Stick with the compounds with RCTs.