Condensation and HTT often go hand in hand. The culprit, for the most part, is the drastic temp changes between inside and outside. You'll notice this mostly in fall and early spring. Many suggest cracking a window...DH would not even think of that because when he's trying to keep the warmth inside, he doesn't want a window open to the colder outside. No point in discussing...that's his way. If you don't have Pop Up Gizmos, strongly suggest you invest in those...worth their weight in gold, Bob is a great owner and very reachable if any questions or problems. We used Hypervent on our front bunk, since it got 99% of the use. It DOES NOT completely eliminate the moisture, but does raise the mattress about an inch above the dampness. In the morning just lift, wipe with a towel and you're good. They are not inexpensive...check online. Back in '06, we paid about $107 for ours for one bunk only. But....felt it was well worth keeping the mattress dry and did an acceptable job. If you're cooking inside in the colder weather, humidity from cooking is a huge problem. Try to eliminate as much moisture as possible when cooking and always, always use your vent fan above the stove and even in the bathroom. If you can use the oven rather than the stovetop, you'll be a bit ahead. The oven will tend to dry the air a bit. Once temps stabilize this will pass. It's the difference that's the stinker.