Prima di dormire, riordino la camera da letto.

Because in Italian, prima di + infinitive is the normal pattern for before doing something.

• prima = before
• di dormire = sleeping / to sleep

So:

• Prima di dormire = Before sleeping / Before going to sleep

You need di here because prima is being followed by a verb in the infinitive.

Compare:

• prima di mangiare = before eating
• prima di uscire = before going out
• prima di studiare = before studying

Without di, the sentence would sound incomplete or incorrect in standard Italian.

After prima di, Italian normally uses the infinitive when the subject is the same as the subject of the main verb.

In this sentence:

• riordino = I tidy up
• dormire = to sleep

The person who tidies up is also the person who sleeps, so Italian uses the infinitive:

• Prima di dormire, riordino... = Before sleeping, I tidy...

If the subject changes, Italian usually uses a different structure, often with che + a verb form:

• Prima che tu dorma... = before you sleep...

But for this sentence, the infinitive is the natural choice.

Riordino is the present indicative, first person singular of riordinare.

So it means:

• I tidy up
• I put in order
• I straighten up

In context, the Italian present often expresses a habitual action, not only something happening right now. So this sentence can mean:

• Before going to sleep, I tidy up the bedroom.
• In other words, this is something I usually do.

Italian usually does not need subject pronouns unless you want emphasis, contrast, or clarity.

The verb ending already shows the subject:

• riordino = I tidy up

So io riordino is possible, but usually unnecessary.

You might use io if you want contrast:

• Io riordino la camera, tu no.
  I tidy the room; you don’t.

In a normal sentence like this one, leaving out io sounds natural.

Not exactly.

Riordinare often means:

• to tidy up
• to put back in order
• to straighten up

The idea is often that something is already messy, and you restore order.

Ordinare can mean to arrange/order, but it also very commonly means to order something, like in a restaurant or online:

• ordinare un caffè = to order a coffee
• ordinare un libro = to order a book

So in this sentence, riordino is a very natural choice for I tidy up.

Yes — in Italian, camera means room, and very often bedroom when the full phrase is camera da letto.

This is a classic false friend for English speakers.

• Italian camera = room / bedroom
• English camera = macchina fotografica or simply fotocamera in Italian

So:

• la camera da letto = the bedroom

Not anything related to photography.

Literally, camera da letto is something like room for sleeping / room for bed, but the real meaning is simply bedroom.

This is a common Italian pattern:

• occhiali da sole = sunglasses
• spazzolino da denti = toothbrush
• sala da pranzo = dining room
• camera da letto = bedroom

So da + noun often describes the purpose of something.

Here:

• camera = room
• da letto = for sleeping / for bed

Together: bedroom

Italian uses definite articles much more often than English does.

So la camera da letto is perfectly natural where English would often just say the bedroom or even my bedroom, depending on context.

Italian often prefers the article even when the possessor is obvious:

• Mi lavo le mani. = I wash my hands.
  (literally: the hands)
• Riordino la camera da letto. = I tidy up the bedroom.

If context makes it clear that it’s my bedroom, Italian does not have to say la mia camera da letto.

Yes, absolutely.

• Prima di dormire = before sleeping / before going to sleep
• Prima di andare a dormire = before going to bed / before going to sleep

The version with andare a dormire is a little more explicit and often sounds very natural in everyday speech.

There is a slight nuance:

• dormire focuses on the act of sleeping
• andare a dormire focuses more on the moment of going to bed / going off to sleep

In many everyday contexts, both work well.

The comma separates the introductory time phrase from the main clause:

• Prima di dormire, = Before sleeping,
• riordino la camera da letto. = I tidy up the bedroom.

This is similar to English, where we often write:

• Before going to sleep, I tidy up the bedroom.

In Italian, the comma is common and helpful here, especially because the time phrase comes first. You may sometimes see short introductory phrases without a comma, but in this sentence the comma is completely normal.

Yes. Prima can mean different things depending on context.

Here it means before:

• Prima di dormire = before sleeping

But prima can also relate to first:

• prima = first / earlier / before

Examples:

• Prima mangio, poi studio. = First I eat, then I study.
• Sono arrivato prima. = I arrived earlier.
• Prima di uscire, chiudi la porta. = Before leaving, close the door.

So the surrounding structure tells you which meaning is intended.

Most naturally, it suggests a habitual routine:

• Before going to sleep, I tidy up the bedroom.

Italian often uses the present tense for habits and regular actions, just like English can use the simple present.

If you wanted to make the habitual meaning even clearer, you could add words like:

• Di solito = usually
• Ogni sera = every evening

For example:

• Di solito, prima di dormire, riordino la camera da letto.
• Ogni sera, prima di dormire, riordino la camera da letto.

But even without those, the sentence naturally sounds like a routine.