Time and pacing are important aspects of comics storytelling. Usually, in humor strips, you go for a snappy last panel with the punchline. Here, the point of the gag is Jeremy sitting half-dozing at the table for a very long period of time. This is shown by having the events of the day pass by in the background, but also through the impossibly long balloon where the word "trött" ("tired") is drawn out over no less than 24 hours.
So here creators Jerry Scott and Jim Borgman use two modes to convey the how tired (and bored) Jeremy is: the passage of time in the background, and how he draws out the word "tired" – and half the joke is that he just couldn't do that in the real world. His mother's "maybe you need more rest" just adds a nice touch of (likely unintended – by her, not by Borgman and Scott, of course) irony.