so, the screen turns off when you lower your arm and turns on again when you raise your arm...makes sense. My pebble has a backlight that that comes on when you flick your wrist etc. both designed to save battery life now...when I'm running, I've noticed that the movement of my arm often triggers the backlight..and after 2 hours I've lost a fair bit of juice..not too important on the pebble with 6 days of bat life...but, on an apple watch? I could charge my watch, go out on a run and after 1 hour find that I have a dead battery because the screen has been on the whole time. thoughts?