I have this problem... definitely! I was never sure what is was and I showed my feet (they were always getting slightly red and would progress (and by progress I mean they would get more and more red though the day) to doctors and they never seemed to think anything of it. (The soles of my feet also go mottled randomly/occasionally with small white spots) Finally one dr said that I did not have much padding on the bottoms of my feet, and they could be turning red because of this, and it could be making the pain worse. So they suggested I have more cushioning under my feet. I switched into Asics (sneakers) which have gel cushioning- and my feet feel so much better when I walk- they aren't cured from pain, but it relieves some strain and therefore the pain reaction to walking in much less. The redness on my soles at night is also reduced.

The *At night* part I don't think has ever really been explained by medicine, but it seem generally accepted that this is one of the ways PN is.