In just three short lines, the speaker sums up a day that blurs from one task into the next. "Off and on" suggests a restless back-and-forth, and "home and office" tells us the two places have run together. Work isn't staying in its own corner. The speaker moves between rooms, or perhaps carries the job around even when sitting at home.
The last line is the strangest and most interesting. Instead of saying that night arrived, the speaker says "busy till night met my eyes." Night seems to catch them by surprise, as if they looked up and found the dark already there. That small twist hints at how absorbed they were, and maybe how little they noticed the day passing.
The mood is tired, matter-of-fact, and a little wry. There's no complaint spelled out, but the clipped rhythm and the lack of any pause or pleasure in the day leave a quiet sense of time slipping away. The title, "Diurnal," means belonging to the daytime, which makes the arrival of night feel like an ending.