just been reading a thing about camping in alaska, the guy who wrote it suggested that a foam mat with either a tin foil backing or a tin foil survival bag laid on it, was the best choice for winter.
he said a inflatable air type mat stayed cold cos your body heat escaped through it.
Tony, some air mats contain insulation to stop heat escaping to the ground. Some of the ‘best’ are the Exped down mats (which contain down obviously), Exped also make one with a synthetic filling. NeoAir mats have a reflective barrier on the inside which doesa similar thing. Any air mat which is ‘open’ and allows air to move freely inside will be cold in winter as it offers no insulation.
A thin closed cell foam mat underneath any mat will bump up the R value by about 2.
Have a look at the mats over at AlpKit, their self inflating mats are pretty good at keeping you warm.