What a difference an article can make! This is an example of one of those subtle uses of the article that can often be missed, and is also an example of why we need to do our exegesis and translation looking at the bigger picture.
Nicodemus comes to Jesus at night, either because that is when rabbis study, or because he did not want others to know. In the case of the latter, it would give us the best example in the NT of the genitive of kind of time; Nicodemus came as one who comes in the night (νυκτὸς).
He addresses Jesus with some politeness in v 2: “Rabbi, we know that you are a teacher come from God.) Note the anarthrous διδάσκαλος; “a” teacher. It isn’t clear how sincere Nicodemus is; but after all he did come, so we should give him some credit.