A thread last week was talking about how sleeping with the lights on was bad for you! (I know, different types, but still....)
The lights would likely be turned off for night time use.
It helps restart the circadian rhythm in the cells, which should require a no light occasion.
Strangely, another study yesterday or the day before talked about doing this in COPD sufferers, yet a different way.
Intense light in the Daytime while you work! Darkness at night when you have sex and sleep!!
(Or just eat orange peel and do those other things :))