Rhodiola Rosea

Rhodiola is an adaptogenic herb with strong evidence for reducing mental fatigue under stress. A 2009 Phase III double-blind study of 161 people showed significant reduction in fatigue and cognitive impairment over 4 weeks. The active compounds rosavins and salidroside modulate cortisol and dopamine pathways. Key distinction: it does not sharpen cognition in already-rested people but is effective at preventing stress-induced mental decline.