vocabulary - Which one is correct: "Do you wake at seven?" or "Do you wake up at seven?"

Someone said to me that the first one is the correct answer, because you use "wake up" to ask someone to stop sleeping. But I think the first one does not sound natural.

Answer

In modern (American) English, "wake" in your example is generally followed by "up". But this isn't always the case.

I don't always like to use NGrams but here's a helpful image that shows the recent trend:

Of course, this misses some various other phrases that are similar, like the command "wake me at 7 am"... which is fine but can also be phrased "wake me up at 7 am".'

So, to answer your question, in modern English, "wake up at" is more appropriate and common but "wake at" is not technically incorrect... it's simply not much in modern use and you may find pockets where it is still quite acceptable.