This may not be from a simple glow stick. The material inside a glow stick wears down and evaporates eventually. This may be from a paint that when applied is activated by a light source. Therefore, when the sun shines on it and lamps are turned on, it activates the material and makes it glow once the light source is removed. It is kind of light those glow-in-the-dark stick on stars you put on ceilings of children's rooms. I suggest removing the drywall and installing new, since I do not know if this can be simply painted over or primed.