Breakdown of O bebê ficou sem sono no cercado e começou a brincar com a chupeta.
Questions & Answers about O bebê ficou sem sono no cercado e começou a brincar com a chupeta.
It literally means became without sleep, but in natural English it means stopped feeling sleepy or was no longer sleepy.
So in this sentence, the idea is not that the baby could not sleep because of insomnia. It is simply that the baby wasn't sleepy anymore.
Yes. Sem sono is a very common and natural way to say not sleepy.
Compare:
This is a very everyday expression in Brazilian Portuguese.