What is cabin fever?

Cabin fever comes from the days when a person lived far from other people and towns. ie, living in a cabin in the woods and the loneliness would become unbearable. There is no "fever" in connection with this. It's just being in one place with out seeing other people or getting out to mingle with others. It could cause harm to your body if say you didn't eat proper meals or let it get you mentally down and depressed. But in general it isn't going to be harmful to your body, just to your mental condition, which could lead to other things

Yeah, it's more a state of mind than a physical illness. A similar condition would be called "stir crazy"...it is like a fidgety boredom related environmental claustrophobia. I always get cabin fever when I am stuck somewhere no matter how long...in a storm, blizzard, or just when my car isn't running, even when I'm in a LOOOOONG line like for concert tickets (outside!) and I always get a mild but longer bout of it waiting for spring to come.

Physically though, it does affect you. You don't usually get as much exercise or fresh air so it can add to getting out of shape and feeling sluggish. If you are actually stranded without proper nutrition or water, it could start with irritation and get increasingly worse and dangerous. If you are getting all dumpy or stressed about it for a long time, then your immunity would be affected, and of course this would be horribly worse if you are stuck with someone who is sick. Getting irritable or angry from it would raise your blood pressure.

Cabin fever describes the feeling of having spent too much time indoors, normally alone or with the same people all the time. And yes, like many unpleasant emotional states, this can intensify your reactions to physical pain.

It's when you have been locked up in your house so long that you can't wait to get out and go do something. I don't think there is actually any pain involved. Maybe some discomfort from all the anxiety.

Cabin fever is being sick of being cooped up.

When you are in a dwelling all the time away from society. Prison is a prime example. Yes it definitely affects you mentally and physically.