Pedestrian alertness during the evening is not affected by lighting conditions typically used for road lighting

A laboratory experiment was conducted to examine the impact of different lighting conditions on melatonin derived from saliva samples, alertness as measured through reaction time (RT) to an auditory stimulus and self-reported sleepiness. This experiment replicated previous work but with the inclusion of an extreme condition to test the null findings of that previous work. There were four lighting conditions as defined by illuminance at eye level and spectral power distribution. Three conditions, having photopic illuminances of 0.5 lx to 8 lx (melanopic equivalent daylight illuminance (EDI) values of 0.5 lx to 10.4 lx) repeated the range used in previous work: the fourth condition extended this to 83 lx (melanopic EDI approximately 100 lx), which is extreme compared to those conditions typical of road lighting. The time period over which measurements were conducted was intended to represent pedestrian activity in the evening. The results revealed a significant reduction in RT and significant decreases in melatonin and subjective sleepiness only with the extreme condition, but did not suggest that lighting conditions typically used for road lighting had a significant effect on any of the dependent variables.