Ao fechar o portátil à noite, sinto que o dia de trabalho termina de verdade.

Ao fechar literally comes from a + o fechar and means roughly on closing / when (I) close.

In Portuguese, ao + infinitive is a very common structure:

• It usually means when / whenever / as / upon doing something:
  • Ao fechar o portátil, sinto… = When I close the laptop, I feel…
• It often describes a habitual or repeated situation or the circumstance in which something happens.
• The subject of the infinitive is normally the same as the subject of the main verb:
  • Ao fechar o portátil, sinto… → The person who closes the laptop is the same person who feels something.

You could think of it as similar to English patterns like:

• When I close the laptop, I feel…
• Upon closing the laptop, I feel… (a bit more formal in English, just like ao fechar can feel a bit more written/neutral than quando fecho).

Yes, you can say:

• Quando fecho o portátil à noite, sinto que o dia de trabalho termina de verdade.

It’s perfectly correct and very natural.

Nuance:

• Quando fecho… – slightly more explicitly temporal: when I close…
• Ao fechar… – focuses a bit more on the action as the trigger of what follows, but in practice the difference is small, and both are very common.

In everyday speech, Quando fecho… might sound a bit more casual and is very frequent.

In Portuguese (especially European Portuguese), it’s very common to drop the possessive when it’s obvious whose thing it is.

So:

• Ao fechar o portátil…
  is understood as
  When I close my laptop…

Some other common examples:

• Lavo os dentes. = I brush my teeth.
• Ponho o casaco. = I put on my coat.
• Vou ligar o telemóvel. = I’m going to turn on my mobile phone.

You can say o meu portátil if you want to emphasise that it’s your laptop specifically, but in this sentence it’s not necessary and would often be omitted in natural speech.

In European Portuguese:

• portátil is originally an adjective meaning portable.
• By itself, used as a noun (o portátil), it almost always means a laptop computer.

So:

• o portátil ≈ the laptop
• um computador portátil = a portable computer / a laptop (more formal/longer)

Gender and number:

• Singular: o portátil
• Plural: os portáteis

In Brazil, people usually say notebook, laptop, or computador portátil, and portátil by itself is much less used as a noun for laptop.

À noite has a grave accent because it’s a contraction:

• a (preposition: to/at) + a (definite article: the feminine singular)
  → à

So à noite literally means at the night, i.e. at night / in the evenings.

Common patterns:

• à noite – very standard for expressing time of day:
  • Trabalho à noite. = I work at night.
• de noite – also means at night, often a bit more generic or in contrast to daytime:
  • Gosto de estudar de noite. = I like studying at night.
• a noite (without accent) – normally just the night as a noun phrase, not a time expression:
  • A noite estava fria. = The night was cold.

In your sentence, à noite is the natural choice:

• Ao fechar o portátil à noite… = When I close the laptop at night…

Portuguese distinguishes between:

1. sentir (non‑reflexive)

   • Often sentir que + phrase = to feel that / to have the impression that.
   • Example:
     
     • Sinto que o dia de trabalho termina de verdade.
       = I feel (I have the impression) that the workday really ends.

2. sentir-se (reflexive)

   • Used more like to feel (in a certain way), often with an adjective or adverb:
     • Sinto-me cansado. = I feel tired.
     • Sinto-me melhor. = I feel better.

In your sentence you’re not saying I feel + adjective, you’re saying I feel that [something happens], so you need sentir + que:

• sinto que o dia de trabalho termina de verdade
  not
• sinto-me que o dia de trabalho… (incorrect)

The choice of indicative vs. subjunctive after sentir que depends on the meaning:

1. sentir que = to feel / sense / have the impression that
   → usually followed by the indicative, because you’re stating what you perceive as a fact:

   • Sinto que o dia de trabalho termina de verdade.
     = I feel that the workday really ends. (This is how I experience reality.)

2. sentir que = to be sorry that / to regret that
   → normally followed by the subjunctive, because it expresses an emotional reaction to a situation:

   • Sinto que o teu dia de trabalho termine tão tarde.
     = I’m sorry that your workday ends so late.

In your sentence, sinto que clearly means I have the impression that, so the indicative (termina) is the natural and correct choice.

De verdade literally means of truth, and in this context it’s an intensifier meaning truly / really / for real.

• termina de verdade ≈ really ends / truly ends

Other options:

• termina realmente
  • realmente = really / indeed, slightly more neutral or formal.
• termina mesmo
  • mesmo is very common in speech as an intensifier: really / actually / indeed.

All three would work:

• …sinto que o dia de trabalho termina de verdade.
• …sinto que o dia de trabalho realmente termina.
• …sinto que o dia de trabalho termina mesmo.

Nuance:

• de verdade – quite colloquial, emphasising genuineness: for real, not just in theory.
• realmente – a bit more neutral/formal and can also mean in fact.
• mesmo – very common in informal speech; can sound emphatic: really, genuinely.

In Portuguese you normally keep the definite article where English might drop the.

• o dia de trabalho = the workday / the working day

In your sentence, you’re talking about your specific workday on that day:

• sinto que o dia de trabalho termina de verdade
  = I feel that the workday (today’s workday) really ends.

Without the article (∗sinto que dia de trabalho termina) is ungrammatical.

You could also say:

• sinto que o meu dia de trabalho termina de verdade.
  This adds a bit of emphasis that it’s my workday, but it’s optional; o dia de trabalho is already understood to be your day from context.

Yes, you can say:

• …sinto que o dia de trabalho acaba de verdade.

Both terminar and acabar can mean to end / to finish, and in this context they’re close in meaning.

Nuance:

• terminar

  • Slightly more neutral or sometimes a bit more formal.
  • Common in written language, schedules, official contexts:
    • A reunião termina às cinco.

• acabar

  • Very common in everyday speech.
  • Also widely used with the sense of being over / running out:
    • O filme acabou. = The film is over.
    • O dinheiro acabou. = The money ran out.

In your sentence, both verbs are natural; terminar just sounds a bit more neutral/standard.

The comma separates the introductory clause from the main clause:

• Ao fechar o portátil à noite, → subordinate clause (time/circumstance)
• sinto que o dia de trabalho termina de verdade. → main clause

Word order and punctuation rules:

• When the subordinate clause comes first, Portuguese normally uses a comma:

  • Quando chego a casa, janto.
  • Ao fechar o portátil à noite, sinto que o dia de trabalho termina de verdade.

• If you invert the order (main clause first), the comma is usually not needed:

  • Sinto que o dia de trabalho termina de verdade ao fechar o portátil à noite.

So in the original sentence, the comma is correct and expected.