The effect of light soaking on a-Si:H films is well known as the Staebler-Wronski effect, though its complete mechanism is not yet clear. The effect of light soaking with UV and white light on intrinsic a-Si:H films was studied. It is shown that device quality a-Si:H films contain a considerable amount of oxygen. The light soaking of the films in the air affected differently low and high-hydrogen a-Si films. It was shown that deep levels in the gap introduced by light soaking are related to oxygen presence. The hydrogen present in the film differently influences the effects of light soaking as a function of its concentration.