笑顔で、いや、寝付けなくてという僕の袖を、彼女が引いた。
I'm sure this sentence actually should have been
笑顔で、「いや、寝付けなくて」 と言う僕の袖を、彼女が引いた。
So it is the man that is having trouble sleeping. And for smiling, it is highly likely the woman that is smiling, because considering the 「」 in the sentence above, the clauses will be
笑顔で、(「いや、寝付けなくて」 と言う僕の袖)を、彼女が引いた。
But the sentence looks like from some novel - there's some possibility that the man is smiling.