These days i seem to get my AF episodes an hour or two after I go to bed. They do tend to be very mild and don't keep me awake or bother me much. They usually last for a few hours although I occasionally go back into NSR after just a couple of hours but that is rare.
What I find interesting is the circumstances under which I go back into NSR. Often, it will just happen gradually, and often I don't even notice when it happens. Other times, an 'event' causes me to go back into NSR.
I have found that a good sneezing session can do this, but I don't find it easy to sneeze on demand. If I'm eating my breakfast too quickly, typically cereal, that has pushed me back into NSR. This morning was a first though.
I was sat on the loo passing a lot of wind, and went back into NSR as a result of it. Coincidence? Maybe, or maybe the straining had an effect.
It does appear though that there can be a number of bodily 'functions' that help going back into NSR.