Stay Slim by Flicking This Switch

Talk about an easy way to lose weight . . . a new study suggests that you could avoid packing on extra pounds just by flicking a switch.

The switch in question? Your bedroom light. Or that patio light that always wakes you up at night. Or that alarm clock that's too bright. A new animal study suggests that being exposed to even just a little bit of light at night might make you fat.

Night Lights
In the study, some mice were kept in darkness during the night while others were kept in dim lighting. And even though the mice in dim lighting weren't fed any extra, by the end of 8 weeks they had gained 50 percent more body mass than the mice who were kept in darkness. The light-exposed mice also started showing signs of prediabetes. Researchers think the extra light at night may have altered the mice's levels of melatonin -- a hormone known to influence metabolism. (Related: Find out how eating dinner earlier can help you sleep better.)

Healthy Rhythms
One of the interesting things that happened with the light-exposed mice is that they shifted their eating times. Mice, being nocturnal, usually do most of their eating at night. But in the study, their natural circadian rhythms seemed to be affected by the light, causing them to eat more during the day instead. And although a great deal more research is needed to understand what affects light exposure has on humans, it could turn out that changes in our circadian rhythms mess up our natural eating times, too, and somehow encourage weight gain. And it syncs up nicely with previous research that suggests that disrupting our circadian rhythms can alter our metabolism. (Related: Check out some surprising ways that too much light may affect health.)

Find out the most effective time of day to work out.