For the case of counterpropagating waves with orthogonal circular polarizations the resulting polarization is linear everywhere, but rotates about z ^ ^ at an angle − − k z . As a result, there is no Sisyphus effect. The rotating polarization instead leads to motion-induced population imbalances in the Zeeman levels that cause imbalances in radiation pressure leading to a damping of the atomic motion. These population imbalances are only present for states with F = 1 or higher.