Multitasking is hardest in the early morning May 07, 2007 Multitasking seems to come easier for some and is virtually impossible for others, however new research shows that it is difficult for all in the late night and early morning. Previous studies have shown that the time of day greatly affects human's reaction time (for a review, see Carrier & Monk, 2000). This performance decrement is constantly found during the night with its' lowest point in the early morning. This leads to the assumption that the time of day directly affects the speed of cognitive processing. Daniel Bratzke at the University of Tuebingen wished to take these studies a bit further and figure out what makes our reaction time so slow during the wee hours. While many researchers have studied this, Bratzke focused on one of the three stages of human processing because he argues that measuring overall reaction time does not allow researchers to separate the effects of three different processing stages. Bratzke describes, for example, that the stage models of human performance assume at least three distinct processing stages: early perceptual, central decisional and late motor. He writes, "Given this widely accepted view, the question arises whether time of day affects all processing stages in general or one or more stages selectively." There is evidence that the circadian variations in reaction time are at least partly due to changes in two of the processing stages; in the early perceptual stage for example, it takes longer to detect and