Dave Bonta packs a whole weary day into a few scraps of language. The speaker is hungover, or at least worn out, and calls themselves a "morning-after rat" heading to the office again. The rat image is unflattering: it suggests someone scurrying along a routine path, a bit grubby and ashamed. "One-eyed" in the title adds to that sense of a half-functioning creature, squinting at the day with only part of its attention.
The second stanza jumps ahead. "Real till night" suggests that the working day is the only reality on offer, something to be endured until evening. Then "the upper bed" appears, which I read as a bunk or a high sleeping place, though the poem doesn't spell it out. It feels like a small refuge at the end of the grind.
The mood is dry, tired, and quietly funny. There is no complaint, only a clipped, self-mocking tone, as if the speaker is too drained for full sentences. The gaps between phrases mimic that foggy, stop-start state of mind.