According to an elementary textbook the New English File (starting with chapter 3/B daily routine) your day starts when you wake up and ends when you go to bed.
But yes, what people mean in real life depends on the situation. On a job interview I wouldn't include the parts of my day that's not related to work but in a different situation, e.g. a journalist asking it, interpreting when your day starts and ends may depend on you.
So generally speaking it does include all 24 hours of the day unless the question is about a specific part of the day or you have reason to interpret it as such.

According to an elementary textbook The New English File (starting with chapter 3/B daily routine), your day starts when you wake up and ends when you go to bed.

But yes, what people mean in real life depends on the situation. On a job interview I wouldn't include the parts of my day that's not related to work but in a different situation, e.g. a journalist asking it, interpreting when your day starts and ends may depend on you.

So, generally speaking, it does include all 24 hours of the day unless the question is about a specific part of the day or you have reason to interpret it as such.