Just a light bulb in a tin can will dispense heat , we used to raise 1 day old ckicks that way in the UK post war days , suitably protected of course , yum-yum christmas feast .

No naked in the house then, put more cloths on !

It's all about conserving heat, not necessarily producing it. Your body produces a lot of heat by itself.

Did you know that about 70% of body heat escapes through your head and feet? (30% through your your hands)?, I have heard tho

So I would guess, your first priority is to cover your feet and your head.

Myth, as proven on myth busters.

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