I have the original Surface Pro with 128 GB. I've been wondering which is the most efficient thing to do when taking a pause. If I'm not going to use the Surface for 1/2 hour or 1 hour --- is it better on the battery charge level to shut it down and restart it or to put it to sleep? Which uses the least energy ... sleep state for a period or shutting down and then rebooting later? The battery apps that come with the unit are pretty useless, certainly not good enough for any real calculations.