When I was testing the app with an iPod, I would run it in the mattress mode for 3-4 hours, then switch to wristband mode and put it on. iPod physically has 1/2 of the battery capacity of an iPhone, so iPhone users are at a big advantage there. It is very likely that iPhone 4 is the only device on the market that can run an app like that overnight, when mounted on a wrist


PS. I just have to say it, I love your avatar