In this talk, we study the growth of Sobolev norms of solutions to Nonlinear Schrodinger Equations which we can´t bound from above by energy conservation. The growth of such norms gives a quantitative estimate of the low-to-high frequency cascade. We present a frequency decomposition method which allows us to obtain polynomial bounds in the case of the 1D Hartree equation with sufficiently regular convolution potential, and which allows us to bound the growth of fractional Sobolev norms of the Cubic NLS on the real line. We will also present some 2D and 3D results.