At first, it sounds very simple, but looking at it some more, it begins to mean more. The rhyme scheme here, for instance. You could have done ABAB throughout the poem, but instead you started ABA and then ended the last syllable of the next line on an alteration of B. That then leads into the rest of the poem, which abandons the rhyme scheme altogether. When you take into consideration the story in the poem, the rhymes and lack thereof begin to make more sense.
In the beginning of the poem, the narrator is preparing to fall asleep. At this point, the narrator still has a fully conscious mind. Where the rhyme scheme breaks, knowing that the rhyme breaks there almost brings to mind the image of the narrator yawning before going to bed. As the rest of poem continues in the same simplistic writing, the rhyming ends completely, and that is the crucial element that makes the second half of the poem give the impression that the narrator is falling asleep.
The thing is, though, recognizing how that works in the poem didn't come about until after taking a look at the syntactical structure of the poem. If you want something like it to truly convey the impression of falling asleep or something of that nature, I would like to suggest, if you would allow me, gradually decreasing the quality of the narrator's speech as he or she falls asleep. Doing so would really help in giving the impression of the narrator losing conscious capacity and drifting to subconscious control. Just my own opinion, though. Do it however you like.
In the beginning of the poem, the narrator is preparing to fall asleep. At this point, the narrator still has a fully conscious mind. Where the rhyme scheme breaks, knowing that the rhyme breaks there almost brings to mind the image of the narrator yawning before going to bed. As the rest of poem continues in the same simplistic writing, the rhyming ends completely, and that is the crucial element that makes the second half of the poem give the impression that the narrator is falling asleep.
The thing is, though, recognizing how that works in the poem didn't come about until after taking a look at the syntactical structure of the poem. If you want something like it to truly convey the impression of falling asleep or something of that nature, I would like to suggest, if you would allow me, gradually decreasing the quality of the narrator's speech as he or she falls asleep. Doing so would really help in giving the impression of the narrator losing conscious capacity and drifting to subconscious control. Just my own opinion, though. Do it however you like.