I suspect that there is more than one "correct" answer. A wool blanket has the advantage of being wider (i.e. can wrap the sides where the hammock compresses the sleeping bag) and has a multitude of other uses, including as emergency garment or sleep system. A closed cell foam pad or inflatable mat is a standard, well know item that needs no introduction. An interesting idea is the Exped Doublemat. A thinner 1x2 m closed cell foam mat. You could leave it unfolded and thus get the "wide" advantage of the blanket, or folded into whatever shape you prefer.
A Rudolph mat (i.e. reindeer) is the one I prefer if I can justify lugging it. It calls for an outer bag in there is rain or in a conoe -- I use an old canvas stuff sack with a trash can liner inside it -- but is fairly indestructible and confortable. But seldom seen in full lenght size, but is usually wider than a regular foam pad (so you get some of the benefits from the blanket).
Summary: there are many options, all of which has advantages and disadvantages. Try the mat you have, see what you like, think and experiment
Last night I used a reindeer hide, with a wool jerkin/waistcoat stuffed into the "corner" where my feet rest to give me some insulation there. There was a book somewhere underneath as well, but that was ok too, but I do not suggest it as a regular sleep mat alternative (the book was in a leatheer cover, so it took no damage). And a wool hoodie under my head as a pillow, and my pants somwhere near my knees i the bottom.
I had exactly the same ... A sticky doesn't work, because people:
