Breakdown of Я встаю на рассвете, но мой брат ещё сонный.
брат
brother
я
I
мой
my (мой, моя, моё) / mine
на
on, at / by (transport) / to (a place) / to (in answer to)
Questions & Answers about Я встаю на рассвете, но мой брат ещё сонный.
Why is it встаю instead of "вставаю"?
The infinitive is вставать (to get up). Verbs ending in -ставать, -давать, and -знавать have a special rule: they drop the -ва- suffix in the present tense. Instead of "вставаю", you just attach the regular endings to the root, giving you встаю.
Why do we use на for "at dawn" (на рассвете)?
While broad times of day use the instrumental case with no preposition (like утром for "in the morning"), specific transitional moments like sunrise (рассвет) and sunset (закат) use the preposition на followed by the prepositional case.
Could I use просыпаюсь instead of встаю here?
You could, but it changes the meaning slightly. Просыпаться means to wake up (open your eyes), whereas вставать means to physically get out of bed. Just like in English, getting up and waking up are two different actions.
Why does the word сонный have a double 'н' (нн)?