I couldn't really think of a place to put the question I was about to ask, so I decided to come here. On my way, I realized I'm probably going to run into this problem more than once due to the sciency nature of the fantasy I'm working on. "So!" I told myself, "Why not keep things nice and tidy in one thread?" And that's exactly what I've done.

First order of business.

My main female character has been cryogenically frozen for a long period of time, most likely for over a century. Supposing that happened to a human on Earth, would it be theoretically possible for his internal body temperature to permanently drop a few degrees and level out at a new, personal normal? What would happen to someone if his "normal" body temperature dropped a few degrees?

I don't know, but I suspect that given how many bodily functions are fine-tuned to specific ranges, I'd guess that even if the person was used to it, that their body wouldn't work as well since different bacteria may not be supposed to survive when the body temperature has been lowered that much... Although it doesn't answer this specific question, the wikipedia article on this may be helpful: http://en.wikipedia.org/wiki/Human_body_temperature

Nevertheless, if this is already fantasy, there's no reason why you couldn't justify a safe temperature drop with other means. And I don't think it sounds that unbelievable. I'd personally go for it.

Although humans can adapt to surviving in a great variety of outside temperatures (there are ways to treat yourself to become immune to discomfort from being cold), the internal temperature of a human doesn't vary much. When it does, you're sick. Hypothermia sets in at 95 degrees generally, and after too long you die. It would, in my belief, be possible for someone to adapt or train himself so that he could survive for longer, but not forever.

As for a smaller temperature shift, it wouldn't kill you, however it deteriorates your health, according to some people. Viruses survive better in a cooler body, circulation slows, and there are a myriad of other nasty things connected to too low of a body temperature. Someone elderly or also someone with a disease like fibromyalgia, chronic fatigue, diabetes, cancer, and others have a decrease in body temperature.

On the other hand, there have also been studies, or maybe just one study, I'm not sure, that might link a decrease in body temperature to longevity.... The study was done on mice, though, and the findings are still in research stage. Also, though I haven't done too much research on it, I believe the way they got the internal temperature of the mice down was to limit their calorie intake, and I think that in itself could be what made them live longer, not the lower body temperature.... * shrugs * Don't take my word for it.

Hrm... what if I localized this to the skin? Could the skin hypothetically stay at a few degrees colder than the body's internal temperature? If I were to go this route, I think I would need the temperature or pain receptors to be damaged too... Lady Rwebhu, you mentioned ways to become immune to discomfort. Could the cryogenics cause my character to be able to easily withstand 30? She'd still feel cold (maybe around 45-50), but no discomfort.

If the issue at hand is figuring out how to make her withstand coldness, I know that there are some people in this world who can just withstand extreme coldness without even flinching. I'm not well-versed in exactly what cyrogenics is, but you might be able to add something like that on...

The issue is two-fold. She needs to (1) feel cool/kinda emit a small level of cold and (2) easily survive in freezing temperatures in the same way we would survive in cool weather.

As far as I know, neither one is a particularly likely side-effect of cryogenics. But it's not like I know a whole lot about that, either.

It already is. The skin's mean temperature, in around seventy degrees fahrenheit surroundings, is around eight degrees less than the rectal temperature (measured in your gut).

Well, I'm not entirely sure about what the cryogenics would do.... It might. It might not. I don't know any of the scientific reasons for the treatment that I know of working. It was just an old friend of mine who told me a story about her father. An Indian told him that if he ran naked in the freezing cold for a couple miles, his body would never feel discomfort from cold again. He tried it (in the woods, ya know...), and it worked. So...that's about the extent of my knowledge on that subject.

There was one of those spend-your-life-doing-something-crazy-til-you're-the-best-in-the-world guys who could submerge himself (except for his head, obviously) in ice water until his skin temperature was forty degrees, a drop of more than half its normal temperature. (His core temperature remained stable the entire time, as well as his heart rate.) He also swims in ice cold water for long distances, and runs marathons in shorts in freezing conditions. So far as I know, he has suffered absolutely no ill affects, and certainly no majorly debilitating ones.

So if the human body is capable of doing something like that, I don't think it's too far of a stretch to have someone who can remain at a lower skin temperature permanently, and who is resistant to cold outside temperatures.

Sounds like the problem's solved. I'll post my next one when I can remember what it is.