We show how optical spectra in dense plasmas are determined by the shift of energy levels as well as by the broadening due to collisions with the plasma particles. In the lowest approximation, the interaction with the plasma particles is described by the random phase approximation (RPA) dielectric function, leading to the Debye shift of the continuum edge. The bound states remain nearly un-shifted, and their broadening is calculated in the Born approximation. The roles of ionization potential depression as well as the Inglis–Teller effect are shown. The model calculations have to be improved going beyond the lowest (RPA) approximation when applying to warm dense matter spectra.