Mean change in PVT reaction time for our four experimental treatments: Control (C), Nap (N), Meditation (M), Sleep Deprivation Plus Meditation (SD+M). Performance improves following meditation (M, SD+M) and declines following a nap and in controls (N, C); Friedman Test Statistic = 23.4, df = 3, p << 0.0005. Treatments noted with the same letter (a or b) denote nonsignificant subsets of the overall analysis. Values represent the mean PVT reaction times before treatment minus the post-treatment. Error bars denote one standard error.