Running battery completely down

I've been wondering about this.....I use an arc AA at work almost nightly and have a question about when to change the battery. After it has gone into "moon" mode it is still making enough light to use but is it hard on the electronics? Should I change the battery when it goes into moon mode or is it safe to always be running the battery completely down? (I've never actually seen it shut off) I've noticed it won't come back on if you turn it off and the battery is very low (but you can let it sit for a few and it kicks back on) anyway, cool to run it way down all the time? /ubbthreads/images/graemlins/icon3.gif

There is no harm to the light running it down until it stops (ws it 0.6V?) and it should not even make the cell leaking (unless you have a real bad cell which leaks for another reason).