Positional PVC's?

I like to read laying in bed before going to sleep each night and I've noticed in recent months that there seems to be a connection between laying on my back for extended periods of time and the PVC's. I can have an average day of perhaps a couple of hundred mild PVC's (which is a "quiet" day for me) and then after an hour or two of reading, I might have a horrible, sleepless night of heart-stopping sensations and jolts. And yet other nights are no problem. So it's not a set pattern, but I tend to think there is a connection.

I also sometimes get couplets and multiples and the worst ones have usually been at night when I've been awakened from a certain position (I tend to sleep on my side or stomach). Sometimes I will get up to around 40 irregular beats in a row. As soon as I sit up or turn around, my heart will go back into its normal rhythm, but NOT until then. Since it's usually the middle of the night and I'm really tired and groggy, they're very mild. I feel them, but they're not as scary as they usually are, and so I've dared to push it and see just how many multiples I get in that position without sitting up. It seems to never get back to normal on its own, and after about 40 or so, I've had enough and change positions to get my normal rhythm back.

On occasion, when bending over forwards to pick something up, I've had some really scary couplets that were so intense that I felt close to fainting.

This tells me that there must be some connection between position and PVC's. I'm just not sure why, but I tend to think that it may have something to do with the vagus nerve (although from what I understand, the vagus nerve affects heart rate more than rhythm), or perhaps some other nerve.