Rolling shutter-based image sensors generate images by sequentially illuminating individual pixel rows. While this often results in unwanted image distortion for scenes with motion, we propose methods to exploit the temporal behavior of the rolling shutter to detect periodic changes. Temporal information can be extracted from single rolling shutter frames, but one is limited by the number of pixels that the motion extends in the frame. However, with several rolling shutter frames we can extract very high frequencies, without aliasing, that are far above the nominal Nyquist limit established for global shutter cameras based upon the same camera frame rate. Applying the Lomb-Scargle periodogram permits a frequency analysis of sources that extend only a few pixel rows in the image.