Foot falls asleep

[AdamGB]

Sounds like an impinged sciatic nerve. Probably By your piriformis muscle

http://www.chiro.cc/health_images/piriformis.gif

You probably have a misalignment at the hip joint. It will only be your right foot because bad posture is rarely symmetrical!

there's a large nerve that comes from your spinal column, through your pelvis and down your hip/rest of your leg, if it's getting crushed by a bone/muscle/tendon it's bound to cause problems.

A similar thing can happen in a nerve that goes through your subcramonial space (inner shoulder) if your shoulders are in a bad position it gets nipped and you'll get pins and needles/other neurological symptoms in your arm and hands.

Seeing as it happens during running etc it's probably down to incorrect technique or an imbalance. I'd go an see somebody to assess your posture and correct it.

Some basic glute/hip flexor/hamstring ( lower complex ) stretches might help.
Particularly the Piriformis stretch, as it is that hip muscle in particular that usually causes sciatica or Piriformis syndrome, the sciatic nerve sometimes runs over it, sometimes over it and sometimes through it depending on genetics so if it's tight, inflamed or out of place it's bound to cause bother.

Unlikely, but food for thought: it could be a magnesium/calcium/other mineral deficiency, but it's probably piriformis syndrome, it's pretty common.