While the whole study is really interesting, if you aren’t interested in reading it we’ll understand. The final conclusions, below, are all you really need to know.
In conclusion, we found evidence of a significant association between exposure to light at night and obesity in humans that was not explained by potential confounders we could measure. While the possibility of residual confounding cannot be excluded, the pattern is intriguing and warrants further investigation, particularly because there could be much potential for preventive measures.
The short version is, sleeping in the dark is important as is limiting your light exposure for at least the hour or so before bed. There is such a thing as sleep hygiene. Keep an eye out, there will be another article about it later this week.