The sterile neutrinos are like ordinary neutrinos as they are spin-1/2 particles that do not possess electric or color charge. But, the sterile neutrinos do not carry weak nuclear or hypercharge. The streile neutrinos are right handed and ordinary neutrinos are left handed.
They can not be normal neutrinos during a switchover.
More here https://arxiv.org/search/?query=sterile+neutrino&searchtype=all&source=header
Oh well, there goes my Nobel Prize...................