There might be cellphone alarm clock apps that you can set to go off with the ringtone of your choice. Surely you can find loud ones online! Maybe you can find one that sounds like a battlefield (I thought of this because of a joke played on a military guy who hit a button on his computer and there were guns booming, and he fell to the floor, as his buddies laughed. No one was shooting, of course! But it might wake you up!).