This isn't new news either. I have heard this several times before.
I will try anything to lose weight and if sleeping with the light off helps I am trying it. I view it not as an excuse for being obese, but just a little something extra I can try to improve my situation, now that I have had counselling for the reason I needed the light on in the first place.
I would add though, sleep itself is the important thing and if someone can't sleep with the light off then it has to be better to sleep with it on. Sleep anxiety can cause stress which increases adrenalin, which in turn leads to cortisol in the body, which can result in weight gain.
Sometimes the choice is between something that is bad for us and something a little bit bad.