Is Valerian extract a diuretic or an antidiuretic?
There is one study that I can find that has been cited in the medical literature that examines individuals taking valerian extract for generalized anxiety disorder. In this paper, there do not appear to be any claims that valerian has any diuretic or anti-diuretic properties. However, that's not to say that those properties don't exist. Additionally, there is no indication that the extract is associated with hyponatremia or hypernatremia, which are two other signs of disorders affecting salt/water balance. Overall, it sounds like if there is a diuretic or anti-diuretic effect of valerian, it is not well-described (yet).