Researchers have discovered links between overexposure to light and depression and obesity:
Randy Nelson, a circadian biologist at Ohio State University, has been studying light’s effects on depression and obesity since 2004, when one of his graduate students was hospitalised for a staph infection. The student complained bitterly about the bright lights in his room and in the hospital hallway, which robbed him of sleep and stressed him out. Nelson and another graduate student, Laura Fonken, decided to investigate this complaint using rodents as experimental subjects. They found that mice who were exposed to constant bright light exhibited depressive symptoms, behaving listlessly and ignoring their sugar-water treats. Remarkably, they then found that the same happened when the mice were exposed to only 5 lux at night, when the animals were normally active. This is equivalent, Fonken notes, to leaving a television on in your bedroom, or a computer screen next to your head as you nod off. …
Along the way, Fonken also noticed something unexpected: the light-exposed rodents got fat, even though they were eating the same number of calories as their dark-sequestered mates. What changed was their circadian rhythms; like a snacky night owl, they were eating when they should have been inactive, upending their digestive and metabolic activity
The Dish 