> 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 「」 and a comma after 笑顔で (、) 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.