Similar story here. During pre-sleep EightyOne-sessions in dark, 1/5 is still too bright so I keep the leds on, illuminating the background to compensate for the overly-bright backlight (I'm somewhat sensitive, I have most of my devices on minimum brightness all the time and it's usually still too much, but at least I enjoy improved battery life...). Once I fell asleep with the leds still on, and woke up about 10 hours later. I was slightly worried about durability of the leds then, but seeing how it happened months of daily usage ago I have learned to "stop worrying and love the phone".
root echo >/sys/class/backlight/acx565akm/brightness 3