We show that the critical density of the Activated Random Walk model on Z d is strictly less than one when the sleep rate λ is small enough, and tends to 0 when λ → 0, in any dimension d 1. As far as we know, the result is new for d = 2.We prove this by showing that, for high enough density and small enough sleep rate, the stabilization time of the model on the d-dimensional torus is exponentially large. To do so, we fix the the set of sites where the particles eventually fall asleep, which reduces the problem to a simpler model with density one. Taking advantage of the Abelian property of the model, we show that the stabilization time stochastically dominates the escape time of a one-dimensional random walk with a negative drift. We then check that this slow phase for the finite volume dynamics implies the existence of an active phase on the infinite lattice.