TL;DR - the amount of light getting in to our rooms when we're sleeping is affecting our
lives.
The study from this article suggests that the amount of light that we're getting in our rooms (from streetlamps/phones/clocks/cars) is having enough of an effect on our bodies that it is causing obesity.
They also found that women who had enough light in their rooms to "see across it" had larger waistlines.
Now, without wanting to overtly offend anyone