But I'm not more aggressive—a behavior change often tied to testosterone. That's not surprising to Robert Sapolsky, ., a neuroendocrinologist at Stanford University and a leading researcher on stress and behavior. "It's really not the case that testosterone 'causes' aggressive behavior," he says. "Instead, it makes the brain more sensitive to social cues that trigger aggression. And in support of that, a guy's testosterone level isn't a very good predictor of how likely he is to be aggressive."
From a CM perspective, the Kidney system is what in charge of the adrenals, sex hormones, vitality, bone development etc. (see “ My Kidneys are What? ” for a general discussion). In general this system can either be overstimulated (what we call Kidney Yin deficiency ) or truly weak (what we call Kidney Yang deficiency ). As far as low testosterone and other symptoms are concerned they can be the same in both cases but in one it is from the body drawing from its resources too much and from the other it has either already tapped them or there is something more functional happening causing lack of production.