I slept very well until 3:00AM.  I was awake, and I kept hearing a cat having sneeze attacks.  I thought it was Stella, but ut tunred out to be Annabelle, who was not in her usual night-time aerie up in the bookcases.  I decided to use the toilet, and all three cats followed me.  Once in the bathroom, neither Annabelle nor Stella had any sneezing fits, and I checked their noses.  So, I went back to bed, Thatch curled up beside me, and I slept fine until the alarm rang.