The GSW-H1000 has several modes that can be activated / deactivated to save battery.
Swipe from the top of the screen and select the cog icon to access settings - then ‘Display’
Screen Time-Out – Recommended 5 seconds, 10-15 seconds will use more battery
Screen Brightness – Recommended level 2 or 3 – 4+ will use more battery
Always on Screen – Keeps the screen on, will not switch to digital PS screen, uses a lot of power
Tilt to wake – Switch this off if trying to save power, instead wake the watch by tapping the screen