Using recently proposed chemistry which includes the NaOH molecule, static calculations simulating the nocturnal sodium layer have been shown to give results in good agreement with an average of sodium measurements. In order to further evaluate this Na layer model, a dynamic time dependent atmospheric photochemistry-vertical diffusion model has been developed to calculate the diurnal variation of sodium and compare it with recent measurements. The diurnal calculations show that the Na model fails to reproduce the measured diurnal behavior of the Na layer, which, for example, shows little variation in abundance between day and night. The situation is further aggravated if we include the reaction NaO2+O→NaO+O2. After a thorough review of the reaction rates it is shown that the major modification which needs to be introduced with respect to the previous model is the elimination of the reaction NaOH+H→Na+H2O. The production of the NaOH molecule is thus effectively transformed into a height dependent sink for Na. The sensitivity of the new model is tested for variations of the reaction rates and the eddy diffusion coefficient and the results are shown to be in much better agreement with experiment.