I spent the morning in the hospital getting poked and prodded and in the end they didn't find anything. The doctors best guess is that while I'm lying down the fluid is building up in my lungs and making it difficult to breath. That was my guess also, which is why I took some Lasix when I woke up feeling out of breath. His advice: Sleep sitting up.

They discharged me later that day much to their delight (I would have been a real pain if they kept me there longer, so yes, it was to their delight).

I've been sleeping sitting up since then and I've been feeling great in the morning.