Concerning the effects of ambient illuminance on arousal, we
found that reading under low ambient illuminance leads to an
increase in the frequency of regressive saccades. Being saccades
strongly connected to fixations, the interaction luminance ⁄ illuminance
revealed that under low ambient illuminance and low
screen luminance fixations are longer (FD) and more frequent
(FR). Finally, longer reaction times to the beep task (RT) were found
under low ambient illuminance, thus confirming that exposure to
lower levels of light intensity can result in decreased performance
(for a review see Section 1).