A Ana deita-se cedo quando está cansada.

In European Portuguese, it is very common to use the definite article before a person’s first name, especially in everyday speech.

So A Ana means Ana, not the Ana in the English sense.

This is normal in Portugal:

• A Ana chegou. = Ana arrived.
• O Pedro está em casa. = Pedro is at home.

In some contexts, the article can be omitted, but A Ana sounds very natural in European Portuguese.

Because the verb here is deitar-se, a reflexive/pronominal verb.

Deitar by itself can mean things like to lay something down.
But deitar-se means to lie down or to go to bed.

So:

• A Ana deita-se cedo. = Ana goes to bed early / lies down early.
• A Ana deita o livro na mesa. = Ana puts the book down on the table.

The -se is part of the verb meaning here.

This is a very typical feature of Portuguese, especially European Portuguese.

In this sentence, the reflexive pronoun is attached to the end of the verb:

• deita-se

This is called enclisis.

In European Portuguese, enclisis is very common in main affirmative clauses:

• Ela levanta-se cedo.
• Ele chama-se João.

In Brazilian Portuguese, learners often see se deita more often in everyday usage, but in European Portuguese deita-se is the usual form here.

In this sentence, deitar-se most naturally means to go to bed.

Literally, it can also mean to lie down, depending on context. But with cedo and the general meaning of the sentence, go to bed early is the most natural interpretation.

So:

• deitar-se cedo = to go to bed early

Cedo is an adverb meaning early.

It does not change form according to gender or number.
So it stays cedo no matter who the subject is:

• A Ana deita-se cedo.
• O Pedro deita-se cedo.
• Eles deitam-se cedo.

It is not an adjective here, so it does not agree with Ana.

Portuguese has two verbs meaning to be: ser and estar.

Here, está is used because cansada is a temporary condition or state:

• estar cansada = to be tired

If Ana is tired at that moment or in that situation, estar is the correct choice.

In general:

• ser = more permanent characteristics, identity, origin, etc.
• estar = temporary states, conditions, locations

So:

• Ela está cansada. = She is tired.
• Ela é inteligente. = She is intelligent.

Because cansada is agreeing with Ana, who is feminine singular.

In Portuguese, adjectives often change to match the gender and number of the noun or person they describe.

So:

• A Ana está cansada. = Ana is tired.
• O Pedro está cansado. = Pedro is tired.
• As meninas estão cansadas. = The girls are tired.
• Os rapazes estão cansados. = The boys are tired.

Portuguese often leaves out the subject pronoun or noun when it is already clear from the context.

In quando está cansada, the verb está and the adjective cansada make it clear that the person being talked about is feminine singular, and from the previous clause we already know it is Ana.

So Portuguese does not need to repeat the subject:

• A Ana deita-se cedo quando está cansada.

You could say:

• A Ana deita-se cedo quando ela está cansada.

But that is usually less natural unless you want special emphasis.

Quando means when and introduces a time clause.

It connects the two ideas:

• A Ana deita-se cedo
• quando está cansada

So it means something like:

• Ana goes to bed early when she is tired.

It tells us under what circumstance or at what time the first action happens.

Yes. Portuguese allows some flexibility.

For example, you could also say:

• Quando está cansada, a Ana deita-se cedo.

This means the same thing, but the emphasis shifts slightly toward the condition when she is tired.

The original order is very natural, but the reversed order is also perfectly correct.

Yes. Using the definite article before a person’s name is especially characteristic of European Portuguese and is very common there.

In Brazilian Portuguese, people can also use the article before names, but usage varies more by region, style, and context. In Portugal, A Ana sounds very standard and natural.

So if you are learning Portuguese from Portugal, it is a good pattern to notice.

You would change the article, the name, and the adjective if necessary.

For example:

• O João deita-se cedo quando está cansado.

Changes:

• A → O
• Ana → João
• cansada → cansado

The rest stays the same.

You would put não before the verb:

• A Ana não se deita cedo quando está cansada.

Notice something important: with não, the pronoun usually comes before the verb:

• não se deita

So in an affirmative sentence you have:

• deita-se

But after não, you usually get:

• não se deita

This is a very important pattern in Portuguese pronoun placement.