The sleep literature reports that integrated measures of road traffic noise levels by themselves (eg Lnight) do not account for all of the observable effects of traffic noise on human sleep, and that level and numbers of noise events in road traffic streams need to be measured. Each of the END and the Night Noise Guidelines for Europe refer to both integrated energy descriptors and noise event descriptors as measures relevant to assessment of human sleep disturbance. At Griffith University we are investigating the occurrence and nature of noise events arising from road traffic streams. Here we examine, based on the literature of experimental and field sleep disturbance studies of road traffic noise, the noise event stimuli utilised in that sleep research. While the notion of an "event" in a noise stream is conceptually unambiguous, there are issues with the application of the noise event concept to streams of road traffic noise, vis-୶is air and rail traffic noise, that need further consideration.