There are clearly both positives and negatives to spending an extended period of time

[Nonverbis]

This is "IELTS Advantage Writing Skills" by Richard Brown and Lewis Richard.

Could you tell me whether it is a mistake in the book?

I mean "positives and negatives to smth". Dictionaries don't seem to show this preposition.

 

[jutfrank]

No, it isn't a mistake in that it's commonly used. We use this to frequently in there-be sentences:

There are several advantages to the proposed action.

You can use it before advantages/disadvantages, positives/negatives, drawbacks, but I'd suggest you only do it in there-be sentences.