Sleeping Bags

I have been sleeping in a sleeping bag for most of the past year. At the start of my senior year of college, I moved into a new apartment and never got around to buying a blanket, so I was in my sleeping bag for the whole academic year. I got a new sleeping bag when I was headed to the Yukon and used it during my months there (for the cold nights, which was most of them, I slept in one bag inside another bag). Now I am back in a new apartment and am using my unzipped sleeping bag as a blanket.

I suppose a sleeping bag is basically an upgraded blanket that can be zipped up into a cozy pocket. Perhaps this customization capability is why I have enjoyed using sleeping bags so much. Are there downsides to using a sleeping bag rather than a blanket? The zipper can be uncomfortable, maybe, but given its placement at the edge, you have to work pretty hard to be inconvenienced by it. Also, depending on the material of your bag, you may or may not feel like you are sleeping under a large pair of snow pants. With all that in mind, I'm surprised there's not a larger market for indoor sleeping bags. A soft, breathable sleeping bag not constrained by the need to be used outdoors could be the next Snuggie-- it's the blanket that never comes untucked!