Ok, so reading this thread made me think that I should consider buying a new set which is small enough to not bother me while I sleep. Seeing the general praise for the sony NC11's, I went over to CompUSA and bought a set. I put in a battery, fitted them snugly in my ear, turned up the stereo with plenty of bass for background noise, then fliped the power switch on the NC-11's to hear... virtually no difference whatsoever. It appears to generate some white noise, but I am skeptical that these headphones even work. Maybe I got a set of duds because these don't even reduce noise as much as my foam earplugs let alone my Targus NC headphones. In fact the noise reduction is pretty much the same whether the power is on or off - indicating that the ear-plug nature of the design is the only thing blocking any noise.
I think I'm going to take these back to CompUSA this afternoon and see if I can get my money back without paying their ludicrous "restocking fee". Caveat emptor.