This is a terrific thread. My C/S has recently been diagnosed, although I've been suffering symptoms for years (in particular the muggy head or headaches when waking). They have been getting worse these days. Gerry's advice on the sleeping position sounds very helpful. I've started to experiment with limited success to date but I'm hopeful. Certainly it is my experience that horizontal sleeping appears to be the trigger. I can be feeling fine most of the day, go to bed and then wake up 7 hours later feeling as though I have not been asleep at all - feeling as though I am jet-lagged.
Sleeping sitting up, or half-sitting up does seem to rest the neck a bit. Until it tries to drop down that is. I wonder have you experimented with a soft neck brace during sleep? I was wondering if this might be helpful in conjunction with sleeping in a semi-upright position. That way the neck would be kept in a good position, even when I nod off.