Juxtaposition in the first two lines: “don’t stay awake too long / don’t go to bed”, they’re two statements that contrast each other and bring an element of uncertainty.
There’s some half-rhymes throughout the poem (“cuddle in your sheets/sang me sound asleep”), and these tend to be present during the ‘happy’ parts (eg memories), and this draws attention to the ‘good parts’.
Full rhymes are used too: “I’m sorry if I tear up . . . You would always make me cheer up”. This is actually part of a stanza that’s follows an abab rhyme scheme, which I guess makes it sound more like a fairytale/nursery rhyme told at bedtime, so it makes it more relatable to people and also more like it’s a story?
And probably the most obvious one is repetition, with the chorus and the bridge and the verses etc. Also some lines are repeated, which I guess emphasises how strongly the speaker feels?
