My hunch is, if you are exposed to viruses aroind or just before your immune system takes a nap, you get sick because you dont have what you need to defend yourself until your immune system rebuilds over the next
week of your
cycle. What helps me...take otc sleep meds to stay rested that
week, hand sanitize constantly, and keep my work/home well washed and cleaned. If I slip up and slack off, I get sick.