I keep all my solar atomic watches face down at night (for some reason they generally only receive in that orientation) and they go into power save mode. If I just turn them over and expose them to the low inside light, they will take some time to "wake up" but they will do so eventually. Otherwise if I tilt the watch back and forth, or shake it, the display comes right up. I'm not entirely sure why that is, but it works. Or, as you mentioned, you can just push a button.