[Sohakes]

I kind of agree about the light. Everyone I know that needs some light on during the night needs it because of some problem. Either the person is afraid of being in total dark, which is a sign of anxiety and is associated with depression, or have some other problem.

I don't like sleeping with the lights on, but it became a necessity because I have frequent sleep terrors where I wake up confused in the middle of my room. A light helps me understand what's happening and where I am faster, and I don't collide into things as much. Sleep terrors are associated with some mental problems, so there would be a correlation between mental problems and the fact that people have the lights on too (considering I'm not the only one who does that), but both things are not causally connected.