All Night Prayer Vigil

I saw a sign saying that there was an all night prayer vigil starting at 9pm at a church next to my campus. My immediate thoughts were as follows:

What good does this do?

Nothing. Do they really think more people will vote if they pray? Do they think their candidate will win the election if they pray for them all night? Can a god effect the outcome of the election?

A more pertinent Question, what harm does it cause?

It is costing students the valuable sleep they need to concentrate in class. By praying all night they have less concentration in their classrooms the following day. This can harm grades and cause people to lose focus on things that actually effect them, like their education.