A hammock doesn’t provide any insulation on its own and therefore you should always use something to cover yourself with when you are sleeping in a hammock. A sleeping bag is not the best option for a hammock as it’s hard to get into the sleeping bag while you are in the hammock. A quilt is a much better option as you simply cover yourself with it. In cold weather a hammock is often paired with underquilt which provides insulation from the bottom.