Answer:
It answers the question why and modifies the verb take.
Explanation:
The adverb clause in the sentence above is Since you're getting up early. Adverb clauses are types of dependent clauses, meaning they cannot stand on their own (the clause above means nothing without the rest of the sentence).
However, adverb clauses do have a particular function in a sentence. Here, it performs the function of an adverb and further modifies, or rather, describes, gives reason to the verb take.
