Keynote looping

With one of the recent updates to Keynote for iOS, looping seems to be enabled - finally! Thanks, Apple. So I intend to use it for a trade show display. What I have found however is that Keynote stops and the iPad goes back to sleep after an indeterminant time. I have had it run for over 3 hours some time and less than an hour at other times. I'd like to keep the show going for the duration of the show, around 6 hours at a time. While I can always restart the presentation, I'd rather it go unattended.

Does anyone know of s setting that impacts this behavior?