Could this effect be explained otherwise by "disruption of normal sleeping environment"? Presumably all of these people are used to sleeping with dim lights. Wh

Could this effect be explained otherwise by "disruption of normal sleeping environment"? Presumably all of these people are used to sleeping with dim lights. What would the effect be on subjects who were used to 100 lux light? My intuitive sense is that light at night has some harmful effect. On the other hand, I live at a latitude where summer nights are very bright, and I and my fellow residents generally get used to it. Perhaps the effect diminishes? Are there people with sleeping habits such that they would find darkness similarly disruptive?