Thanks to all the comments here, I changed into my lightweight J Crew yoga pants and top in the bathroom on my DTW-FRA flights this weekend. Since I fly NW and KL where no PJ's are provided, I've never really seen anyone do this, and I never thought of trying it myself. Well, what a difference in comfort!

I used the paper towels on the floor method (lavs in business class aren't any larger), and put my slacks and sweater into a small tote. When I exited the lav, the purser gave me a smile and said "you sure look comfy". I snuggled into my pashmina and sailed off to dreamland for a good 4 hours. I then reversed the procedure right after breakfast. I swear I slept better, and I KNOW I looked better when I arrived. Just another great idea courtesy of my FT girlfriends