By the end of M Night Shyamalan's 'The Visit', it is evident
that the fake Nana and Pop Pop were lunatics with a medical condition. Now, I read that some of the traits displayed in the movie by Nana are similar to actual conditions. Meaning some patients do behave like that.
But what was the deal with 9:30? Is it possible that a condition like this happens around a fixed time? Or is it simply employed by the director to create more suspense?