Many people become noticeably more alert the moment a room goes dark. A hallway that feels ordinary during the day may suddenly seem unsettling at night. Familiar sounds appear louder, shadows look different, and the imagination begins filling in details that cannot be seen.
Children commonly experience fear of the dark, but many adults do as well. Psychology suggests this reaction is not necessarily irrational. In many cases, it reflects how the human brain responds when visual information becomes limited.
