Light elicits robust nonvisual effects on numerous physiological and behavioral variables,
such as the human sleep–wake cycle and cognitive performance. Light effects crucially rely
on properties such as dose, duration, timing, and wavelength. Recently, the use of methods
such as fMRI to assess light effects on nonvisual brain responses has revealed how light
can optimize brain function during specific cognitive tasks, especially in tasks of sustained
attention. In this chapter, we address two main issues: how light impinges on cognition via …