Assuming that there's not an issue with diseases spreading around, and that there's little to no issue with food allergies, what would the effects be of taking someone from a tropical climate to one that's cold and lacks a sun? They would be regularly exposed to small fractions of "sunlight," but no sun or true equivalent to a sun.
Edit: Sorry, I really should've explained the "fractions of sunlight" part better. Thank you for informing me! The background is that the sun (which was made via magic... alchemy I think? It's where you put a bunch of specific stuff together with some inherently magic things and it makes something) was a giant glowing flower (it makes more sense in context I promise) and when it died it left behind glowing pollen which basically everyone started collecting immediately, and they probably had quite a bit from beforehand too because hey, lanterns are a good thing to have. The pollen is not nearly full strength even if you managed to gather all of it in one place, but large quantities in a small area are capable of growing some crops and providing moderate warmth provided that the area is small and well insulated, but not enough to grow anything remotely tropical.
I hope that helps!