Recessed lights are typically installed in areas of high traffic areas like kitchens, hallways and family rooms. Canned lights are either IC rated, insulation contact rated, or non IC rated, which cannot come into contact with insulation. If additional insulation has ever been added to your home you may want to check that the insulation contractors put some sort of protector around the light before blowing more in. Typically in homes built before 1995, non IC canned lights were used, but I have seen plenty of newer homes with non IC rated canned lights installed. You can find out if your lights are IC rated by going in the attic and looking at the nameplate of the metal light. There is usually a label glued on top of the light that says the specifications of the light and it will say, “IC Rated”.
Recessed lights in a two story home can also contribute to the stack effect if there are enough lights in the ceiling. The stack effect is when warm air rises and is replaced by cool air entering the home through outside penetrations and duct leakage. The stack effect and air leakage can be stopped by air sealing the home including the canned lights. To find more information on how canned lights can contribute to the stack effect in your home check out this article by the Pennsylvania Housing Research Center.
For a guide on ways to seal up your home check out Energy Star’s publication on air leakage and air sealing your home.