The ever-increasing use of sodium discharge lamp, being most economical among all of this type has evoked a wave of studies on the action of this lighting source. The aim of the paper was to evaluate the effect of illumination provided by this new type of high-pressure sodium discharge lamp with improved coefficiency of transmitting the colours (HPSM) on selected visual functions, as well as to compare with results having been established in illumination by filament lamps (GL) and standard sodium discharge lamp (HPS). HPSM are more closer to white light, thus more profitable for sight physiology system and central nervous system than standard sodium discharge lamps. The intention fo the paper was to obtain the answer whether in comparison with filament and standard high-pressure sodium discharge lamp, the new mode of illumination provides better psychophysical conditions complying with the used ergonomic principles, and if there is any possibility for HPSM to be applied for illuminating the closed spaces. The study involved 63 persons, aged from 17 to 54 years. The comparative group comprised 50 persons, who were subjected to the tests with filament and standard sodium illumination. All the studied subjects were divided into 3 age groups (I-to 30 years, II-31-40 years, III-over 41 years). The following visual functions were studied: acuity of far looking vision, proximity visual point, field of vision, time of conscious reaction minimal, medium and maximal, and the number of mistakes during the performed test, convergent, divergence fusion for distance and proximity as well as manual spatial visual localization. All the said examinations were carried out three times within morning hours and in this way gaining the possibility of evaluating the dynamics of functional changes in time (Fig. 1-9). The obtained results were compared with those established after having performed the same tests under standard sodium lighting and filament illumination. Conclusions resulting from the performed studies: 1. The obtained results provide confirmation of stimulating effect of both sources of sodium lighting exerted on the central nervous system. 2. This effect was expressed by: improved visual acuity for distance and reduced number of mistakes at the time of reaction as well as selection in all the age groups, increased divergence fusion for proximity point in persons of I group as well as pertaining to the peripheral visual field in all the studied age groups. 4. All of the above features become evident particularly strongly during the evaluation of the dynamics of the cited functions. 5. The obtained results suggest that the use of HPSM for illuminating rooms could be worth trying.