Sure, you can sleep on it. That's why you brought it, right?
I brought lots of things with me into Peace Corps that didn't make it back. There's no way I would have lugged all that stuff to Morocco just to have it sit in a bedroom for 27 months. Even if it didn't last the whole time, I still got use out of it while I could. Nothing lasts forever.
You can take care of your things to try to make them last, but think about it: the whole point of purchasing anything at all is to use it, use it up and wear it out. (Except for those weird people who keep toys in their original packaging in hopes that they might increase in value. They're no fun.)
I've never used a blow-up sleeping bag for that long, but if I'd had one in Morocco, I would have just put it in my room and used as a regular mattress. Obviously, I wouldn't stab it with knives, put out cigars on it, raised litters of stay puppies on it, or anything like that. When I left town to go work across the country for a week, I would consider either deflating it or raising it in some way, but that would have been only because I had mice. Essentially, common sense would rule.
But you better believe had I brought it, I would have used it, even if it meant throwing it out full of holes after eight months of blissful nighttime dreams.
You get, IIRC, 80 pounds of checked baggage for Peace Corps. The mattress weighs what, six, eight pounds? That's 8-10 percent of your ENTIRE inventory for Peace Corps. Sleep on the thing!
As it was, my sleeping bag (what my host mom called my "sleep pocket" and had absolutely no understanding of what it was) was a fantastic sleep aid in the winter.
And lugging it back, unused, two years later would have been a waste.
Peace Corps 07-09