I'm a student, and, sadly, I spend a lot of time sitting. Before my primal blueprint-induced weight loss, I sat with my legs crossed (ankle over knee) quite often, and it took up to fifteen minutes for me to feel a change in circulation.
However, now that I'm eating clean and a lot lighter, my top leg falls asleep almost instantly. It's not a huge concern, but it happens at inopportune times. There have been times when I crossed my legs out of force of habit near the end of class and end up staggering comedically out of the classroom.
I'm not worried about health concerns, but it does have my curious. What causes this?