 Sad doesn't just stand for a standard American diet. There's a condition known as seasonal effective disorder that's characterized by increased appetite and cravings, along with increased sleepiness and lethargy that begins in autumn when light exposure starts to dwindle. This now appears to just represent kind of the far end of a normal spectrum of human behavior. We all appear to eat more as the days get shorter. There's a marked seasonal rhythm to calorie intake with greater meal size, eating rate, hunger, and overall calorie intake in the fall. In preparation for winter, some animals hibernate, doubling their fat stores with autumn abundance to deal with the subsequent scarcity of winter. Genes have been identified in humans that are similar to hibernation genes, which may help explain why we exhibit some of the same behaviors. The autumn effect isn't subtle. Our research has calculated a 222-calorie difference between calorie intake in the fall versus spring. And this isn't just because it's colder. Since we eat more in the fall than the winter, it appears we're just genetically programmed to prep for the deprivation of winter that no longer comes. It's remarkable that this day and age of modern lighting and heating that our bodies would still pick up on environmental cues of the changing seasons enough to affect such major influence on our eating patterns. Unsurprisingly, bright light therapy is used to treat seasonal affective disorder, nearly tripling the likelihood of remission compared to placebo. Though it's never been directly tested, it can't hurt to take the dog out for some extra autumn morning walks to maybe help thin off some of the coming holiday season weight gain. It's funny, people blame the holidays for overeating, but maybe instead of the holidays causing heightened intake. Maybe the heightened intake that goes with the fall caused the holidays to be scheduled then in the first place. Regardless, other specific recommendations for the prevention of obesity by improving the circadian system health based on varying degrees of evidence include sleeping during the night and being active during the day. Sleep enough, at least seven or eight hours a night, early to bed, early to ride. Short naps are fine contrary to popular belief. Daytime napping does not appear to adversely impact sleep at night. Avoid bright light exposure at night and sleep in total darkness when possible. And make breakfast or lunch your biggest meal of the day. Don't eat or exercise right before bed and avoid eating at night completely.