The speaker is lying in bed over the holidays, half-drowsy, and can hear the sea nearby. Instead of finding the sound soothing, they react with a gentle, joking complaint: the sea ought to go out and take a nap itself, at least at Christmas.
The humor comes from treating the sea like a person who never stops working or never stops talking. We usually think of waves as restful, but here the constant noise is something that could use a day off. The idea of the sea "dozing" is funny because it is so unlikely, and it quietly shows how restless and endless the water is.
The mood is light, sleepy and affectionate. There's no real anger in the speaker's tone, just the lazy, slightly grumbling voice of someone who wants a quiet holiday and talks to the sea as if it were a noisy neighbor or a relative who can't sit still. The short lines and plain wording make the poem feel like a passing thought, caught just before sleep.