They will probably make them extended since there are more crowds at that time.
The park hours are up on disneyland.com and it looks like on the weekend the park will be open until midnight.
I think he ment how do the grad nights affect park hours.
But I don't have an answer for that. I never have been near Disneyland on those nights,but I know the park is open exclusively for the students into the wee hours of the morning. But when they close the park to everyone but graduating seniors I don't know.