Informant: “At the end of each theater performance a lone light is pulled onto the stage because legend has it that without a light ghosts play around and will mess up the set so you have to leave a light on”
The informant heard another version of the folk belief which says that “the light is turned on so that when the ghosts go to play around on the stage they have a light to see and don’t bump into things on the stage.”
The informant learned about this folk belief when he served as a member of the technical theater production crew for his high school. The light would be set “in the middle of the stage every time there was a set onstage, from the first time work is begun on the set until the last night of the performance.” The informant said that this tradition was passed on from the older crew to the younger crew informally because the younger crew would learn from example when they saw the older crew place the light on the stage. According to the informant, this was not an important duty and was actually seen as something akin to a chore. As a member of the technical crew, the informant would have to “drag the light out every night” after the performance. Putting up the light was “just something that needed to be done before the tech crew could go home.” Also, according to the informant, the light consisted of “a light bulb on top of a portable light stand.”
The informant does not believe in the “superstitious” reason for putting up the light, but he says there are practical reasons for the light. The informant said “the reason for the light is so that no one walks onto the stage in the dark and trips over something and breaks it.”
The informant said that the light is important because the tech crew sometimes has to work on the set after hours, and they have to cross the stage to get to the electrical panel to turn on the set lights. Thus, it is helpful to have a light so they can see and not bump into things on stage or fall off the stage. In addition, the crew has put a lot of effort into making the set so they want to prevent it from being damaged.
I thought this was an interesting folk belief because not only does this belief have superstitious roots, but it is also extremely practical. From talking with the informant and from online research, there are many different theatrical superstitions, and some are more common and widely used than others. From what I could find, this particular folk belief is very popular, even the Broadway stage uses the ghost light.