I suppose if the university this student attends were in Alaska, or if she lived in Siberia, she might legitimately take time to inform her reader about the association between “night” and darkness.
We are, however, in Connecticut, where her family also resides. So I’m afraid this is another example of the reaching-for-an-opening-profundity syndrome that afflicts many student writers, especially first-years.
She was planning to go on to distinguish between ideas associated with the darkness of night: fear, wonder, romance, rest. So a reader who did NOT have a blog might have given her a pass on this sentence as a set-up for those that were to follow.
Me, I quietly and supportively wrote “unneeded” in the margin and during office hours suggested other ways she might establish her basic thought. But I also copied the original statement in the back of my grade book, vol. 40 of the Book of Horrors.
I do associate words other than “night” with the idea of darkness, and ideas other than darkness with the word “night.” I’m sure everyone does. I toyed with making a couple of lists here, but that might be an enjoyable parlor game for readers so I will not indulge myself at your expense.
As “today” moves into “this evening” and then “tonight,” though, I encourage you to contemplate the idea of darkness—absent, approaching, and then very much here…at least until “dawn” and “tomorrow.”