Tele-serials have several cognitive effects. It can be noticed that people are getting addicted to different kinds of television serials now-a-days. From the survey it is found that tele-serials have bad cognitive effects and it increases the negative behavior. Till now no significant study of the tele-serials on the effect of cognitive behavior based on technical parameters is done. In this work, the effect on cognitive performance is investigated based on the variation of alpha and beta relative band energy and entropy. EEG Data is acquired from the subjects using Mobita-32 channel wireless EEG data acquisition system. However the recorded EEG signal is contaminated with noise and needs to be de-noised before further analysis. Choosing a suitable mother wavelet function and smoothing method, removal of artifact noise is possible. In the proposed work different mother wavelets are implemented to select the most compatible one with the EEG signal recorded. The minimum mean square error (MSE) and higher signal to noise ratio (SNR) are the criteria chosen to determine the denoising efficiency. The features considered for examining cognitive performance are calculated before and after denoising process are shown in this work. Also the proposed work shows a significant variation in a person's cognition after watching tele-serials on a regular basis.