To track the alertness changes of 14 subjects during a night driving simulation study traditional alertness measures such Visual Analog Sleepiness Scale, Alpha Attenuation Test (AAT), and number of Microsleep events per driving session were used. The aim of the paper is to assess these traditional alertness measures regarding their mutual correlations, revise one of them (AAT) and introduce new more general methods to capture changes in human alertness without too many constraints attached. The applied methods are utilizing data fusion methods and data discrimination capabilities via Learning Vector Quantification networks. The advantage of using more general data analysis methods which allows one to assess the validity of proposed alertness measures and opens possibilities to get a more comprehensive knowledge of obtained results.