Satellite measurements as well as thousands of nights of ground-based photometry show that the pulsation amplitudes and frequencies vary during stellar rotation (short-term) as well as long-term stellar cycles with time-scales up to decades. Even in normal A/F stars, both the stellar light output and the amplitudes of radial pulsation can vary by 0.1% during a rotation. The signs and sizes of the frequency changes during a stellar cycle strongly depend on the m value of the affected pulsation mode.