Dave Bonta's short poem sets two kinds of time against each other. The sea, huge and always moving, "belongs to the present," while everything else, the whole weight of what came before, has "gone to rust." The past here isn't just over; it has decayed, turned brittle and orange.
Then the poem shifts to a stranger place, "where madness / is half moon." The moon is only half there, and it shines so brightly that it "aches." The speaker seems to feel that light as something physical, almost painful. The title, "Lunacy," points to the old idea that the moon stirs up madness, and the last line, "raving in my sleep," suggests the speaker is caught in that state, unable to control it.
The mood is eerie and dreamlike. Judging by the imagery, the speaker may feel cut off from the past and unsettled by the present, with only a sleepless, glowing night left.