The defects produced in 4H-SiC epitaxial layers by irradiation with 200-keV H⁺ were characterized by low-temperature photoluminescence. These defects induce sharp luminescent lines, the so-called alphabet lines. Their intensity shows an evolution under UV-laser irradiation not previously observed. By monitoring the change in the resulting photoluminescence spectra versus time, we distinguish two original ‘families’ of peaks called PB₁ and PB₂. They display a different, and opposite, behaviour with laser irradiation but they are strongly correlated. In particular, the recovering rate of the PB₁ family and the growth rate of the PB₂ family are the same, indicating a structural rearrangement of defects.