Board Thread:Questions and Answers/@comment-5149755-20150529050330/@comment-67.246.92.187-20180211084031

They seem to be only on floor 1 so my best guess is that they are just lights that adjust to the outside lighting, kind of like nightlights with a dimming nob.

I am pretty sure it is to help the new players adjust to SAO by allowing them to see their surroundings and not get scared by what if's in the dark.

That makes since to me anyway.