That's really interesting. I imagine nociceptors have a baseline firing rate but your brain tunes it out because it's just noise. If you switch that off, the current filter system would get whacked out of balance, you'd feel awesome, but when it switches on again, baseline firing would be a salient input for a bit and you might notice it? Of course, long term up/down regulation of various receptors occurs too, but I've never heard of this particular effect before though it sounds plausible to me.

I wondered a while back if (theoretically) taking some kind of non-harmful but pain stimulating compound might not make you feel awesome the rest of the time, and might even be good for you by recalibrating your inflammatory response and such.

BDSM has been shown to improve mental health in a number of ways. http://onlinelibrary.wiley.com/doi/10.1111/jsm.12192/abstrac...

See: spicy food.

I was thinking of something more systemic, but that may be an example.

If you've ever wondered why people on hard drugs like to take off their clothes when they're coming down, this is it. You can't handle the sensory overload of your t-shirt against your skin.

Hard drugs isn't a category of drugs, but powerful opiates seem to be what's included anyways. I'm not aware of opiate users habitually taking off clothing. Other powerful drugs can make you feel cold, adding clothing. Some people really sweat on acid, which is probably a decent cause of taking off clothing.