Saturday night when I went to my hammock it was 34 degrees and my tarp and Poppa Smurf sock (draped over the hammock foot end) were soaked in condensation. When I turned in I pulled the sock up along the ridgeline to my waist to be able to easily pull it all the way up if needed. When I awoke with a chill it was 12 degrees and my tarp ( as expected) was covered in frozen condensation.
But the sock, covered in condensation, fully open to the elements over my waist, with only the heat escaping from my feet and legs was still wet! Very impressive heat trap!