During a week that my city had no electricity, I used a Quark AA, on moonlight mode, in the bedroom when I slept. I wanted to have SOME light on, because I didn't want to fumble around in total darkness when I woke up, but not too much light.
I just left the Quark on moon mode and had it shining across my bedside end table where my glasses, phone, and other stuff were located. That way I could immediately locate and grab the important stuff in the middle of the night after waking up. When your eyes are fully night-adapted, the moon mode is plenty bright enough to see your way around a bedroom.
On a AA rechargeable battery, the Quark AA will run for
315 hours on moon mode (see thread ref. below). So at 10 hours per night, you're looking at about a full month between battery changes! There may be some slight runtime variation from one sample to the next, but they should all be pretty close to that I'd think. The runtime plot can be found in this thread, post 118.
4Sevens Quark Round-up Review: Q123, QAA, Q123-2, QAA-2 - RUNTIMES, COMPARISONS