Previous studies have shown that unusual eating times, light exposure at night, and night/rotating shift work contribute to the disruption of the circadian rhythm resulting in higher risks of sleep disorder, obesity, cancers, in addition to adverse effects on mental status and academic performance. The present review explores how changes in the light and food environments with the times influence human biological rhythm and their potential relationships to metabolic syndromes as well as the slim body trend among young women, which is becoming a social problem in modern Japanese society. Additionally, previous studies on the effects of food and light environments have been introduced for insights on the problems triggered by biological rhythm disruption.
