used theremarests for years - never had a puncture - but i do check where im pitching the tent/thermarest
best ones (for me) are the old Guidelite (now Prolite 4) - light enough on a bike or to hike - though still 4 season - even at -15 here in Canada ! and they keep my hip of the deck when im lying on my side.
you only need to worry about moisture vapour from your breath at higher altitudes - where it will condense in the pad - and freeze if cold enough - wrecking it.
cheers
Grif
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