The Holstein-Biberman equation describing the evolution of the excited
atom population in a dense sodium vapour optically saturated by a sho
rt resonant light pulse was solved numerically. Results were compared
with the solutions for a weakly excited vapour. It was found that in a
strongly excited medium the decay of the Na(3P) atoms is faster than
in the case of the weak excitation. A subnatural decay of the resonanc
e fluorescence signal for some experimental geometries was predicted.