The overall atomic mobility of AOT reverse micelles. in CCl4 as a function of the molar ratio W = [D2O]/[AOT] has been studied with an elastic neutron scattering experiment. The measured intensity suggests that, for small contents of water, the average reverse micelles mobility increases as a function of the hydration. A marked departure of the estimated mean square displacements from low hydration conditions has been revealed above W = 1. Such a hydration-dependent dynamical activation is in agreement with previous NMR and dielectric measurements. The dependence of the atomic mean square displacements as a function of W has been explained by taking into account for the existence of two different dynamical contributions from more mobile completely-hydrated and less mobile partially-hydrated headgroups.