Numerous parameters such as subject age, region of activation, and stimulus timing are known to affect the BOLD signal following neural activation. Here, we investigated how differences in the rest time between successive long visual stimuli alter the kinetics of the BOLD signal in the visual cortex. We found that the BOLD rise time varies with the inter-stimulus interval. By taking this into account when performing statistical analyses of BOLD data, we show that a roughly 20% increase in statistical power can be achieved. In addition, the dependence of the BOLD signal rise time on the inter-stimulus interval provides insight into the physiology underlying the post-stimulus undershoot.