I have had some lengthy discussions about this with friends and done some reading on the subject as well. What I found out is that the claim that "Sensible Sweat" stops under certain conditions (as Stephenson says) of temperature or humidity is simply wrong. There are lots of well documented articles (search "Google-Scholar") on the subject of sensible sweat. None suggest it ever stops. Yet, some, not all, who try a VBL are able to sleep without accumulating condensation. So here is my question. Where does the water vapor go if it doesn't condense on the VBL?