How to re-order an Eloquent collection?

I've got a collection of records retrieved via a relationship, and I'd like to order them by the created_at field. Is this possible in Eloquent?

Here is how I am retrieving the collection:

$skills = $employee->skills;

I'd like to order this $skills collection by their creation. I've tried $skills->orderBy('created_at', 'desc'); but the Collection class does not have an orderBy method.

I guess this problem is very simple and I'm missing something..

via f7n