Learn Portuguese (Portugal): O bebé está só a fazer a sesta.

In European Portuguese, short adverbs like só, já, sempre, or ainda frequently intrude into the continuous tense. They are placed directly between the conjugated auxiliary verb (está) and the preposition a. This sounds very natural and flows better in everyday speech than putting the adverb at the very beginning or end of the clause.

Could I put só before the verb, like O bebé só está a fazer a sesta?

Yes, placing só before the conjugated verb is also grammatically correct and very common. However, inserting it between está and a is a distinct rhythm feature of European Portuguese that native speakers use heavily to make the sentence flow more smoothly.

Why does Portuguese use fazer (to do/make) for taking a nap?

In Portuguese, you do a nap rather than take one. The set phrase is always fazer a sesta. If you try to use tomar, which is used for taking medicine or a shower, it will sound like a direct translation from English and unnatural to a native speaker.

If I wanted to use apenas instead of só, would it go in the same place?