Learn Hardcore Portuguese (Portugal): Se eu ficar muito tempo acordado, o dia torna-se um fracasso. - If I stay awake for too long, the day becomes a failure.

If you said Se eu estiver muito tempo acordado, it would be grammatically possible but less natural; it sounds like you’re just describing being in that state, not the idea of staying up or remaining awake. Ficar is the usual verb for “stay up late / stay awake” in Portuguese.

What tense/mood is ficar in Se eu ficar? Why not Se eu fico?

Ficar in Se eu ficar is in the future subjunctive.

Infinitive: ficar
Preterite 3rd person plural: ficaram
Remove -am → ficar (future subjunctive stem)

So eu ficar (future subjunctive) looks the same as the infinitive, but it’s a finite verb form here.

Portuguese uses the future subjunctive after se (if) when you’re talking about a possible future situation:

Se eu ficar muito tempo acordado, o dia torna-se um fracasso.
If I (should) stay up for too long, the day becomes a failure.

Using Se eu fico is unusual; it would sound more like a habitual description and is not the standard pattern for if + future outcome. The normal structure for these “if in the future, then…” clauses is:

Se
- future subjunctive → present (or future) in the main clause
  e.g. Se eu ficar acordado, amanhã vai ser difícil.

Why is it acordado and not acordada? Does it change with the speaker’s gender?

Acordado is a past participle used as an adjective, meaning awake. As an adjective, it agrees in gender and number with the subject:

If the speaker is male: Se eu ficar muito tempo acordado…
If the speaker is female: Se eu ficar muito tempo acordada…

So in your example, acordado just assumes a male speaker (or a generic masculine). A woman would normally say acordada.

Is the word order ficar muito tempo acordado fixed? Can I say ficar acordado muito tempo or ficar acordado por muito tempo?

The word order is not completely fixed; several options are acceptable:

ficar muito tempo acordado
ficar acordado muito tempo
ficar acordado por muito tempo

All three are grammatically correct and understandable.

Subtle points:

muito tempo before acordado (version 1) is very natural and common in European Portuguese.
por muito tempo (version 3) sounds a bit more explicit or formal: for a long time.
Putting muito tempo after acordado (version 2) is fine; it just shifts the rhythm slightly.

In everyday speech, ficar muito tempo acordado and ficar acordado por muito tempo are probably the most typical.

Is the se in Se eu ficar the same se as in torna‑se?

No, they are two completely different words:

Se eu ficar… → se is a conjunction meaning if.
torna‑se → se is a clitic pronoun, used here as a reflexive / pronominal pronoun.

So:

First se: if (introduces the condition)
Second se: part of the verb tornar‑se (to become / to turn into)

Why is it written torna‑se and not se torna?

This is mainly a European Portuguese word‑order rule for pronouns.

In European Portuguese, in a normal affirmative main clause starting with the verb, unstressed object pronouns usually come after the verb and take a hyphen (enclisis):

O dia torna‑se um fracasso.
Eu levanto‑me cedo.
Eles sentaram‑se.

You use se torna (proclisis, pronoun before the verb) when there is a “trigger” before the verb, like a negative word, certain conjunctions, etc.:

O dia não se torna um fracasso.
Quando o dia se torna difícil, eu…

In Brazilian Portuguese, pronouns before the verb (se torna) are much more common even in simple affirmative sentences:

BR: O dia se torna um fracasso.
PT: O dia torna‑se um fracasso.

So torna‑se is the standard European Portuguese form in this context.

What exactly does tornar‑se mean here? Could I say O dia fica um fracasso instead?

Tornar‑se means to become / to turn into / to end up as. It expresses a change of state:

O dia torna‑se um fracasso.
The day becomes a failure / ends up a failure.

You could say O dia fica um fracasso, and people would understand, but:

tornar‑se is the more typical verb for become (something abstract like a “success/failure”).
ficar often means to end up / be left in a certain state, or is used more with adjectives:
- O dia fica estragado. (The day ends up ruined.)
- Fiquei cansado. (I got tired / I ended up tired.)

So tornar‑se um fracasso sounds more idiomatic and slightly stronger than ficar um fracasso in this specific sentence.

Why is there a comma after acordado? Can I change the order of the clauses?

The comma separates the if‑clause (subordinate clause) from the main clause:

Se eu ficar muito tempo acordado, → subordinate conditional clause
o dia torna‑se um fracasso. → main clause (result)

When the if‑clause comes first, Portuguese normally uses a comma there.

You can reverse the order:

O dia torna‑se um fracasso se eu ficar muito tempo acordado.

In that order (main clause first), you usually do not put a comma before se.

Why is it um fracasso (a noun) and not the adjective fracassado? Could I say O dia torna‑se fracassado?

Fracasso is a noun: a failure.
Fracassado is usually an adjective or a noun meaning failed / loser.

Portuguese normally uses the noun with verbs like ser and tornar‑se in this meaning:

O dia é um fracasso.
O dia torna‑se um fracasso.
O plano foi um fracasso.

Saying O dia torna‑se fracassado is possible, but it sounds odd and very unusual; fracassado is not typically used to describe a day. It’s more often used for people (um homem fracassado) or long‑term projects.

So the natural expression is tornar‑se um fracasso, using the noun.

Why do we need the article um in um fracasso? Could we say O dia torna‑se fracasso?

Portuguese usually uses an article with a predicate noun (a noun that comes after verbs like ser or tornar‑se) when classifying something as a kind of thing:

Ele é um génio. (He is a genius.)
Isto é um problema. (This is a problem.)
O dia torna‑se um fracasso. (The day becomes a failure.)

Without the article (O dia torna‑se fracasso), it sounds ungrammatical or at least very strange. There are a few fixed expressions without articles, but this is not one of them.

So um is necessary here to make it a normal, natural noun phrase.

Does o dia mean literally the day, or more like my day / the whole day?

Literally, o dia is the day, but in context it often has a broader, more personal meaning, similar to English:

o dia here ≈ the whole day / my whole day / how the day turns out

Portuguese often uses the definite article for something that’s understood from context:

O dia correu bem. (The day went well.) → usually means my / our day went well.

You could say o meu dia to stress that it’s specifically my day, but o dia alone is already very natural in this kind of general statement.

Is this sentence also natural in Brazilian Portuguese, or would Brazilians say it differently?

It’s understandable and correct in Brazil, but Brazilians would usually adjust:

Pronoun position
- EP: o dia torna‑se um fracasso
- BR (more common): o dia se torna um fracasso
Very natural Brazilian version might be something like:
- Se eu ficar acordado por muito tempo, o dia se torna um fracasso.
- Or more colloquial: Se eu fico acordado até muito tarde, meu dia vira um fracasso.

So:

European Portuguese:
Se eu ficar muito tempo acordado, o dia torna‑se um fracasso.
Typical Brazilian Portuguese:
Se eu ficar acordado por muito tempo, o dia se torna um fracasso.

Your original sentence is perfectly fine for European Portuguese, and essentially correct for Brazilian Portuguese aside from that pronoun placement preference.