Two groups of Ss (ten each), experimental and control, served as Ss under five different series of stimuli: (1) Red light; (2) Careen light; (3) Sound of 40 db; (4) Light (R x G) and sound. mixed; and (5) Light and Light (R x G) mixed to measure the impact of sleep deprivation (SD) on simple and complex RT (SRT and CRT). The last two series, of a simple automatic electrical reaction time apparatus was used for recording data. We started with following three hypothesis (1) RT in CRT conditions will have greater impact on SD; (2) under SRT condition there should not be any significantly different impact of SD on visual and auditory signals; end (3) of the sub-conditions of CRT, namely, light x sound and light x light, the effect of SD will be more pronounced in case of Light x Sound condition. The first and the third hypothesis were sustained. The causative factors behind some of the results were suspected to lie with the information processing functions of our nervous system. Results have been widely discussed and explained in light of various available theories.