On a windy day, do you feel a draft that starts upstairs or from your attic? Do you get uncontrollable ice dams on your roof no matter how much venting you add? Recessed Lights could be one of the issues. Most likely you have more issues than just recessed lights, but it is a great starting point. (The photo above shows cold attic air being drawn into the home through a recessed light due to the blower door running).
Recessed lighting on the first floor is not our concern, rather recessed cans in your top level that are installed via your attic or ceiling crawlspace. Older recessed lights are most likely not Insulation Contact (IC) rated, this means that any insulation touching them is a fire hazard. If your home does have IC rated lights, it's alright to have the insulation directly on top of the cans, however that insulation is doing nothing to block the airflow as heat can still transfer into the attic.
The issue is that under normal heating conditions heat leaks through these cans and enters your attic – effectively heating your attic which leads to ice dams. Another issue is on windy winter days, cold air is entering your soffit and/or gable vents and can then get forced down through the recessed lights into the heated portion of your home. If you have many recessed lights on the top floor and live in an area with harsh winters, then you most likely have felt cold drafts and wondered where they could be coming from.
The solution(s): in an ideal world the home owner would all together get rid of recessed lights on the top level and install drop down fixtures that were sealed in the attic with expanding closed cell spray foam (or caulking). OR, they would at least install some new IC rated recessed lights as well as an insulated and air tight dome over top of the lights (photo: Tenmat recessed light covers).
Once the new lighting solution has been installed, the homeowner can add more insulation to there attic and safely cover these new light fixtures
Having an Energy Audit performed on your house will show you all the energy inefficiencies within your home and also give you solutions (i.e. the best way to vent/add insulation to your attic).