I'm trying nowadays to pay attention to symptoms and patterns. I've noticed that the nap followed by tingling in hands and feet is typically followed by heat.

My hands and feet get cold quite often now, so I've been trying to nap lately to get them warm again. It invariably works even if the nap is short.

Anyway, I think it must be vascular, as suggested, at the same time as nerves are affected, or shortly thereafter.

I wonder what cortisol does to/for/with/against B12. Stress of course typically affects cortisol levels and we know stress depletes B12.

Whatever chemical it is that's being released after I nap - I wish I knew what it was. Then I'd take more of it from other sources. The 'tingling' isn't painful or annoying; it's almost comforting. It seems to be related to the body's effort at healing.