Warm Feet Please,

[Timelord]

This is an interesting one. I have always been one for keeping some layers on and I even slept in my boots a few times whilst in artic conditions. i was fine but thsi may not be the crux of the issue. You see, I am generally warm blooded (thermal regulated) and so maybe that was why I was ok.
The points you have made have sparked my interest - Because recently an experienced aquaintence told me a rather different story about keeping feet warm in a sleeping bag. I always was aproponent of the layering system (more on this further down) but my friend told me that they were trained to not wear boots in sleeping bags as the body circulation system would sense the feet were warm enough and that combined with restricted circulation due to the boot constriction, then resulted in the blood supply being lessened to the feet. hence a net cooling result. Now I am not sure about this and it could be worth looking into - a bit like the drinking warm tea in a hot climate to induce pores opening wider and sweating so as to reduce the temperature - but in reverse.. Also the person told me that layering up inside a sleeping bag was also bad because then the body effectively had the same thing going on and also the body perspiration could not be expelled easily. This would also be contributory to a cooling effect over time but with the body wrapped in many layers, the skin temp sensory regulation would be confused and could expel heat too much instead of conserving it.
It is a thought provoking theory and definitely worth looking into. My aquaintence said they were taught to wear only 1 good quality thermal base layer and then have something like a snugpack softie or buffalo jacket over the top, so that the perspiration could wick away easily, whilst the down or similar jacket fillings would efficiently insulate their bodies.
Just to reiterate, they said they were instructed to strip to base layers & no boots inside their quality sleeping bags and then in the morning they would have the benefit of dressing in dry warm clothes. The clothes were wrapped in a bag or something like that (can't remember) and placed inside the sleeping bag overnoght to keep them warm & dry.

As for socks - I always wear military artic wool socks in a white/offwhite colour. Sometimes with a red line or two running around the top edge. These have always been warm, even when wet occasionally. Also, they allow the foot to breath and so my incidence of water or sweat related complications is minimal. I am not a fan of most man made fibres as they do not always perform well when wet or under prolonged hardship. beware goretex lined boots, as if you go wading a stream higher than your boot tops, then you will be wearing a very efficient pair of waterproof bags, only with the water on the inside - and drying those out will not be easy. Cambrelle leather lined boots are softer & better insulated and dry out far quicker if ant water enters. Traditional waterproofing treatments such as dubbing are very effective anyway. going off topic, so will end it there. TL.
(Oh yes, I do not advise the all in one adult baby grow type garments as they are man made nylon type affairs and will cause sweat & heat to be trapped. they will also likely melt onto your skin if exposed to fire.)