%0 Journal Article
%T White Light During Daytime Does Not Improve Alertness in Well
%A Domien G. M. Beersma
%A Marijke C. M. Gordijn
%A Renske Lok
%A Roelof A. Hut
%A Tom Woelders
%J Journal of Biological Rhythms
%@ 1552-4531
%D 2018
%R 10.1177/0748730418796036
%X Broad-spectrum light applied during the night has been shown to affect alertness in a dose-dependent manner. The goal of this experiment was to investigate whether a similar relationship could be established for light exposure during daytime. Fifty healthy participants were subjected to a paradigm (0730-1730 h) in which they were intermittently exposed to 1.5 h of dim light (<10 lux) and 1 h of experimental light (24-2000 lux). The same intensity of experimental light was used throughout the day, resulting in groups of 10 subjects per intensity. Alertness was assessed with subjective and multiple objective measures. A significant effect of time of day was found in all parameters of alertness (p < 0.05). Significant dose-response relationships between light intensity and alertness during the day could be determined in a few of the parameters of alertness at some times of the day; however, none survived correction for multiple testing. We conclude that artificial light applied during daytime at intensities up to 2000 lux does not elicit significant improvements in alertness in non-sleep-deprived subjects
%K human
%K light
%K alertness
%K daytime
%K dose-response curve
%U https://journals.sagepub.com/doi/full/10.1177/0748730418796036