The speaker opens like a gentle nature lover, listing the nighttime sounds he enjoys: crickets, an owl, waves on a lakeshore, even a crowd of sleepless teenagers howling at Nelson Ledges. The tone is warm and appreciative, almost like a small hymn to the night.
Then the poem turns. What he can't tolerate are the noises his friend's lover makes, which keep him awake at one-ten, two-thirty, three-fifteen and four. The humor comes from the contrast: after all that praise for loud, wild sounds, he draws the line at this one. The list of times makes his sleeplessness feel painfully real.
The speaker sounds exasperated but good-humored. He stays polite ("Friend," "I'll gladly"), yet the offer to flee to Lake Erie or the "lemurs" is dryly sarcastic. The mood is playful and comic, a politely worded complaint about a very awkward problem.