Light At Night Linked To Weight Gain Perhaps Due To Shift In Eating Times

This has got to be the key.

In an article published in Proceedings of the National Academy of Sciences they found that mice exposed to dim light during their sleeping hours for a period of eight weeks had a 50% higher weight gain compared to mice that slept in the dark. Even reducing their food intake and making them do more exercise did not bring their weight down to that of the other mice that slept in the dark, unless they made sure the availability of food matched a mouse's natural eating times.

Shut your eyes.

And you mouth.