I've found that while I never could function very well in the heat before - once PN onset its been much tougher.. and alsio the exhuastion factor gone up astronomically... the slightest exertion results a nap - which I've never been one to take in my life - and not out of laziness - my body is just zapped.... (although feet feel like icecubes!) even in 100 degrees....

Autonomic neuropathy I know affects my ability to handle (or not) handle heat - I literally got heat exhaustion going to the doc this summer during one of our heat waves and ended up being treated for that instead of the real reason for my visit...... Could you have some autonomic dysfunction going on?

Also, other side of the coin - at night I get much colder - I now sleep in socks sometimes in the winter - (since PN) - never did that in my life either - just cant seem to get them warm......

(your meds may be contributing also to your ability to handle heat and/or exertion - for example I know I take a heart med that hampers my stamina etc......)

Feel better....