Questions & Answers about Quando eu estou cansado, prefiro não pegar o volante.
Both are correct.
In Brazilian Portuguese, subject pronouns like eu are often optional because the verb form already shows who the subject is. So:
- Quando eu estou cansado...
- Quando estou cansado...
both mean the same thing.
Including eu can add clarity, emphasis, or simply reflect a more natural spoken rhythm for some speakers.
Because estar is used for a temporary state or condition, while ser is usually used for more permanent characteristics.
So:
- estou cansado = I am tired right now / at the moment
- sou cansado = sounds unnatural in this context
If you want to say you feel tired, sleepy, exhausted, sick, etc., Portuguese usually uses estar:
- estou cansado
- estou doente
- estou com sono