The poem reads like a series of small observations from someone who hasn't slept. A screech owl is calling at four in the afternoon, an odd hour for a night bird, which hints that the speaker's sense of time has come loose. Even tap water seems to be "still moving" as it's drunk, as if everything has become strangely alive and restless to a tired mind.
The third stanza looks back. The speaker remembers trembling after days without sleep and feeling invincible, a feverish high that sleeplessness can bring. But the ending deflates that memory. Gray fur spreads through the coffee grounds, probably mold, and the speaker is "bleary-eyed again." The mood is groggy and slightly eerie, with a dry humor running underneath. The title mentions a new theory about why we sleep, and the poem seems to answer it in its own way: the body's wild energy fades, and what's left is exhaustion and a morning ritual gone bad.