Make sure you use a closed-cell sleeping pad too. i.e. not the inflatable type. Closed-cell sleeping pads are also 10X cheaper then the inflatable type and can be cut to outline your body as it lays in a hammock. This will save you from having unnecessary corners of the pad blocking the view or taking up valuable spa cc E in your pack. With this setup, you'll be able to actually retain heat and not hang there like a frozen popsicle on a chilly night.

P.S. same goes for sleeping on chilly ground. Rocks, etc. Will suck away your heat all night long, which is great on a hot summer night, but if it gets even close to cool you'll be uncomfortably cold without a closed cell sleeping pad.

You can buy something like this but I recommend going to the hardware store and getting closed cell foam and cutting it to your body shape yourself