Looks good. How did you get that glow around the objects? I've been trying to find out how to do that. Do you use a custom shader?
I like the idea of the game, but unfortunately I don't get that stressed feeling I'd expect to get from this game. Maybe it's the lack of music. You should have a sound of sand falling down on each hourglass, and some alert sound when an hourglass is about to be emptied. I think that would make a big difference. Either way, cool idea, a little more polish and it would have been awesome!
Good luck next game jam! :)