>>529
sleeping on top of a sleeping bag is lumpy
inside it is more or less the same deal
i can imagine that there would also be very little to stop the sticks, roots, rocks and ground from bothering you.
i have never used an inflatable mat but it looks like an inflatable version of those mats
if they deflate as fast as an air matress you will be out of air really fast in that tiny thing.
get a foam mat and put a sleeping bag on top of it like >>816 says, you get the stiffer support you need