But I remember the old saying that you lose your sense of smell while you sleep (or at least in the deep phase of the cycle). Apparently that was why unattended fires late at night are so dangerous because you lose your early-warning system of smelling smoke, so by the time you wake coughing (if you even wake) it is often too late. Admittedly my “knowledge” of that is anecdotal, from long ago, so anyone more knowledgeable feel free to correct me - I won’t take it personally.