Metabolic and physiologic effects of acute exposure to artificial light at night

This thesis investigated the metabolic and physiologic effects of acute exposure to artificial light at night (ALAN) in nocturnal and diurnal rodents. White and blue light caused glucose intolerance and affected food intake in a sex- and wavelength-dependent manner in Arvicanthis. In rats, we observed effects of light in locomotor activity (LA), energy expenditure (EE), respiratory exchange ratio (RER), food intake, and hepatic expression of clock and metabolic genes in a time- and wavelength-dependent fashion. In mice, white and blue light decreased LA; when fed a free-choice high fat high-sucrose diet an improved glucose tolerance was observed after light exposure. HFHS-fed animals exposed to blue light increased fat intake. Both wavelengths increased chow food intake when we used melanopsin mutant mice. Mice exposed to ALAN showed an altered EE, RER, and plasma glucose levels in a time-dependent manner. We showed that an intact molecular clock is necessary to observe metabolic disturbances caused by ALAN using BMAL1 -/- mice. These effects were dependent on the wavelength, indicating that ipRGCs, cones, and rods may be part of the pathways involved. We provided further evidence on the need for caution when being exposed to ALAN, to prevent detrimental metabolic consequences.