On my windowsill, amongst the other pots, there is one that contains some Jambu tress (Syzygium samarangense) When they first started I used to regularly look at them at night and say (my god, they thing look wilted I better give them water tomorrow morning only to go the next morning and see it perky. I took me months to realized that all that was happening is that Jambu's are one of those trees that goes to "sleep" in the dark (tucks all it's leaves down). I rather suspect that, if it got no dark it would burn itself out.
BTW NYboy, quick favor to ask. The next time your in your office (next Mon, I'd assume could you rub one of the young leaves on your lemon and tell me what it smells like). For a few years I've had a lemon tree I grew from a pit and it has this quirk I've never seen before; it's young LEAVES smell like lemons, as opposed to petigrain (that general "clean" scent most citrus leaves have.) I'm still trying to find out if this is normal for lemon trees, of if I have some sort of odd freak.
Just saw this, yep leaves smell like lemons. You can make tea with he leaves. So far grow lights have been on 24/7. Very little leaf drop, which happens when bringing inside, they grow new leaves for the lower light.