In a randomized, double-blind, placebo-controlled trial, 90 patients with idiopathic chronic fatigue were given 1 g or 2 g of panax ginseng or placebo daily for four weeks. Self-reported mental fatigue scores were significantly improved in the groups given ginseng compared to placebo.
Kim HG, Cho JH, Yoo SR, Lee JS, Han JM, Lee NH, Ahn YC, Son CG. Antifatigue effects of Panax ginseng C.A. Meyer: a randomised, double-blind, placebo-controlled trial. PLoS One. 2013. 8(4): e61271