When I awoke around 6:00 AM my back was quite cold. I think it was from sweat, but the thought crossed my mind that it could be condensation too. I used a Big Agnes pad with a North Face 15F down bag for insulation. I was also wearing 2 layers of wicking shirts and a fleece on top (making it had to tell if I was sweating), with long underwear and double layer sweats on bottom.
I felt REALLY cozy and warm as a I was waiting to go to sleep around 2AM, so I was really excited to get a full night's rest. The only semi cold spots were my shoulders, but they weren't touching the hammock, and were cover by the bag. Needless to say I was quite disappointed when I woke up.
One thing I learned, is sleeping with your head in the bag is a bad idea in the winter... especially with down. Though it didn't cause me to be cold, had I stayed out longer, I think the down would have become quite wet. I guess I'll have to wear more intense headwear next time.
Any ideas how to prevent sweating (I think) on my back? I think if this hadn't happened I would have been in great shape. I'll be happy to give more details if anyone wants to understand the situation better. Thanks a lot.