A. Basic Sleep ScienceVII. Aging and Neurodegeneration p=0.014), and orbitofrontal (0.021, 95% CI: 0.009-0.034, p=0.001) areas. A post-hoc analysis showed similar trends throughout the brain. Conclusion: Baseline EDS was associated with a longitudinal increase in FDG-PET signal. This hypermetabolism may represent a compensatory mechanism in response to efficiency loss in the setting of overloaded synaptic activity. This hypothesis is consistent with previous findings suggesting increased blood flow at the end of the waking day when compared to blood flow after a night of sleep. However, the increase predicted by EDS does not imply an overall increase in brain metabolism, because the magnitude of the reduction predicted by baseline age is higher than the increase in FDG-PET signal predicted by EDS in all regions. Introduction: Light, particularly blue light, increases alertness, performance and cognitive brain responses, but age-related decrease in the effects of light has been reported. The extent to which these age-related modifications are caused by changes at the level of the eye (because of senile miosis and lens yellowing) or the brain is unclear. Methods: We conducted a neuroimaging protocol including 14 younger (20-30y), 12 older (60-80y) and 12 matched older healthy individuals with intraocular lens replacement after cataract surgery (IOL subjects), i.e. they differed from the healthy older group only in terms lens light absorption. Subjects completed two functional magnetic resonance imaging (fMRI) acquisitions while performing a working memory 2-back task (2b) and a simple letter detection "0-back" task (0b), once under blue monochromatic light (B) (480nm, 3x1013ph/cm2/s) and once under orange monochromatic light (O) (620nm, 3x1013ph/cm2/s). Each fMRI session was conterbalned and also included blocks of n-back task in darkness, as well as blocks of light alone (B, O). Results: First, all blue blocks were contrast against blocks completed in darkness [(2bB+0bB+B)-(2bD+0bD)]. Results revealed common group effects with greater brain activations in lateral geniculate nucleus, lingual, calcarine sulcus and median occipital gyrus under blue light exposure (P corrected < 0.05). As a second step, in order to estimate non-visual impact of light, we computed the effect of blue versus orange light on cognitive brain responses [(2bB-0bB)-(2bO-0bO)]. Results revealed a main effect of group (P corrected < 0.05) with group differences in various regions including the cingulate cortex, median prefrontal cortex and hippocampus. Young subjects showed greater brain sensitivity to light as compared to IOL and older individuals. No significant differences were found between IOL and older with their natural endogenous lens. Conclusion: Our results confirm that the aging brain is still sensitive to blue light. However, both older groups showed reduced non-visual effects of light on cognitive brain responses as compared to the young. These results suggest that cerebral modifications, not the lens, underlie age-related reduced...