We report on the thermal annealing of light-induced neutral dangling bonds (DB's) created by strong band-gap illumination at 77 K and room temperature (RT) in amorphous silicon-nitrogen alloys ( a-Si1-x Nx :H). We find that the light-induced DB's are annealed out with distinct distributions of annealing activation energies (E A's). The distribution for the light-induced DB's created in the fast process (FDB's) and the one for those created in the slow process (SDB's) are separated unambiguously: E A for FDB's is in the range from 0 to 0.7 eV, in which two separated peaks (centered at about 0.09 and 0.4 eV) are embodied, and E A for SDB's is in the range from 0.6 to 1.4 eV, centered at about 1 eV, in a-Si0.5N0.5:H. Moreover, the results demonstrate that the distributions of E A for FDB's and SDB's depend on illumination temperature and illumination time.