Sinus issues - only at night

I'm lucky to be free of allergies and serious sinus issues. I can't recall my last cold. However, over the past several years I've started having nighttime-only sinus issues that are interfering with sleep.

Several hours after I go to bed, one side of my sinuses gets completely blocked (the side on which I'm laying). This wakes me up. By turning over, the blocked side usually clears after a few minutes but then the other side becomes blocked. I turn again. You get the picture. This apparently occurs at light point in my sleep cycle and I often have trouble getting back to sleep.

Here's the interesting thing. When I get out of bed in the morning, the blockage clears up almost immediately, typically within 20 seconds! I have absolutely no sinus congestion during the day.

I can't use nasal decongestants due to childhood overuse -- a single application triggers a rebound affect. My doctor gave me a sample of Astelin Pro to try. However, it wears off before the night is over - typically 5 hours or so. (It could be that the sinus blockage happens earlier but sleep is too deep for me to awaken.)

I considered the possibility that my down pillow could be causing an allergic reaction. Just to be sure, I switched to a foam pillow about a week ago. I also recently purchased a new bed (not because of my sinuses!). None of these changes made a difference.

I really hate to medicate. I've only used the Astelin 3 or 4 times, but enough to know it doesn't last long enough. If I were to get out of bed to use it after having been asleep for a while, I would definitely have trouble getting back to sleep (a common problem as we age). Same issue for Pseudoephedrin. I don't think a timed release version is available.

Any suggestions or replies from others who suffer from this problem would be greatly appreciated.