Darkness makes you slim? Constant light at night creates excess weight.
Persistent, weak but constant light at night can favor the overweight of people. Even if you pay attention to a healthy diet and sufficient exercise, this effect occurs. This is reported by scientists from the US University of Ohio.
50 percent more weight gain from dim light
The researchers wanted to investigate how light sources can affect people at night. On this occasion they undertook an experimental arrangement with mice. To do this, the scientists exposed young mice to a weak but constantly burning dimming light at night. The result: the animals gained around 50 percent more body weight within eight weeks than the mice, which were exposed to a normal “light-dark pattern”.
The researchers stated that the reason was that the mice had eaten at the wrong times. "Something in the light made the mice eat at the wrong times in our study when they would normally degrade the food," said study author Randy Nelson. Because if the animals were refused to eat at these times, they did not gain weight either. All rodents received the same amount of food and had a similar amount of exercise. "The mouse experiment shows how important the timing of eating is when it comes to weight gain," said study leader Laura Fonken.
Obesity is a health problem in the western world
Obesity has become a mass phenomenon in western industrialized countries. It results in numerous diseases such as diabetes or heart attack. The researchers now wanted to investigate the question of which other factors - in addition to a lack of exercise and an unhealthy diet - play a role. They assume that the widespread obesity in western countries is also favored by constant light sources. Electric light sources can be found everywhere at night. In the apartment it is the television or computer, on the street the cars and street lamps.
Hormone production is disrupted
The experts suspect that the continuous light interferes with the body's melatonin production. The hormone melatonin is responsible, among other things, for controlling the day and night rhythm. This control is crucial for the metabolic process in the body. If the metabolism is disturbed, obesity could result. At one point, however, the study was unable to provide a concrete answer. Unlike humans, mice have a different sleep and active rhythm. Mice are naturally more active at night and eat only 36 percent of the day.
Other studies also point to correlations
Other studies have repeatedly pointed to the connection between being overweight and sitting in front of the television or computer for hours. However, it has always been assumed that those affected do not invest enough time in sports and healthy eating because they are constantly watching TV. But it could also be that people "eat at the wrong times animated by the light", Randy Nelson believes.
Regardless of this study, scientists from the University of Bristol, England, provided a report that demonstrated that ten to eleven-year-old children who spend more than two hours watching TV or using the PC are at increased risk of mental illness. The researchers also concluded that the risk for the children is independent of physical exercise and balance. The study was published in the science magazine "Pediatrics". The light sources study D was published in the science journal "Proceedings of the National Academy of Science (PNAS)". (sb, 2010-10-11)
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