Scientists at the Ohio State University conducted experiments with three groups of mice. One group was subjected to 16 hours of standard light and 8 hours of darkness. The second group was exposed to 16 hours of standard light and 8 hours of dim light. And the third group was immersed in standard light for 24 hours a day.
When these mice were allowed to eat all they wanted for eight weeks, all of them gained weight, but the group that experienced 8 hours of darkness gained the least. The reason for the difference turned out to be the timing of the feedings. While all mice consumed similar amounts of food and had the same amount of exercise, those that were exposed to darkness ate less during the day—a period reserved for sleep for these nocturnal animals.
The scientists subsequently confirmed this observation by restricting meals to the times when the animals would eat under normal circumstances. In this experiment, none of the mice gained any weight.
Together, these findings led the researchers to conclude that meal timing is critical for weight management and that bodily sensors for hunger are greatly skewed by inappropriate exposure to light (day for nocturnal creatures and night for those of us who are diurnal).
Of course, this experiment was conducted in mice, not humans. Therefore, results could only be extrapolated to be relevant to our human experience. Nevertheless, rodent research often leads to useful human discoveries.
So, if you are trying to maintain a healthy weight or lose a few pounds, sleeping in the dark—as nature has always intended—may help you achieve your goal.