Yeah, the only 2 things that pushes darkness are lightning strikes(1s) and boss explosions(5s). Glowing enemies & keys were suggested before but iA didn’t add it.
I can see why you didn’t notice that lightning pushes out darkness because the background is still dark and it doesn’t make much sense like that, iA should make it more noticeable like make the background be normal at these 1 or 5 secs then it fade again to dark.