I was coughing all night too with a cold recently. I figured a lot of the "tickle" that caused me to cough was due to post-nasal drip, so I took Nyquil every night, and it helped, though it only lasts 6 hours. I didn't want to take another dose when it wore off (and the coughing started back up) because I knew it would keep me sleeping all morning, so I'd take plain cough suppressant when I'd get up in the middle of the night.

I also slept on the couch for about four nights when I was at the worst portion of my cold. We live in a 1BR condo, and the couch is much more comfy for me than my DH because I'm short. I actually slept just fine on it, and my anxiety level was lower b/c I didn't worry about waking him up all night long if I coughed.

Hope you feel better soon! I am still coughing a couple of times a night two weeks later, but not taking any meds, and it's gotta be gone soon, I hope!