• Question: After sleeping on one's hand for example, numbness sets in - followed by intense pins and needles as the cells can't get the oxygen they need: How long can it stay without flowing blood before the hand will be paralysed? I've heard that even a few seconds without oxygen (flowing blood) will cause the cells die, but surely it's got to be more like several hours (or even days)?

    Asked by sammieblues to David, Luna, Mark, Melanie, Probash on 22 Mar 2011 in Categories: .
    • Photo: Melanie Stefan

      Melanie Stefan answered on 21 Mar 2011:

      A few seconds seems awefully short, but in a matter of hours or days yes, tissue will die if the blood supply is cut off. (That’s why the guy in “127 hours” managed to cut his hand off, because it had died off within a few hours, so he did not feel the pain)

    • Photo: Luna Munoz

      Luna Munoz answered on 21 Mar 2011:

      I would think that it would not be seconds, since people may fall asleep on a limb and will not wake up paralyzed.

    • Photo: David Pyle

      David Pyle answered on 21 Mar 2011:

      Another interesting question – but I don’t have the answer!

    • Photo: Probash Chowdhury

      Probash Chowdhury answered on 22 Mar 2011:

      What you’ve been told is true – however, the dead cells can easily be replaced by new cells. However, if the sheer number of dead cells is too much that’s when parts of the hand will die. This rarely happens from falling asleep on your hand (I’ve done it loads of times and I still have all my fingers and hands). But in first aid they used to say that if you had blood pumping out of your arm you should stop the blood flow by using a tournaque (tying a piece of rope or something around the arm near the top) to stop the blood flow. The problem was that people left the tournaque in place for too long and the arm or had would die. How long is too long? Not sure but an hour would definitely do it. They don’t allow it in first aid any more.

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