The ones I know on suppressants are of course better when their allergy is taken care of. But usually it doesnt last very long; other things surface instead. I have close family members and work colleagues on a list of these. They all complain about low energy except for the fact that they sleep better on a med called Zyrtec; some doctors even use this as a sleep aid. And for hangovers :-)
Back to vitamin D; I would like the ones on vit D3 to keep reporting back of their experience with it; I believe there is more to reveal about the matter.