Do you think this might be caused my carpal tunnel syndrome? Is there any pain in your wrist as well? Unless you remember a certain injury that you may have had, you could also be using your hands too much, such as playing the piano or typing...

When you are sleeping you could be clenching your fists or bending your wrists so that you decrease the circulation and cause pain throughout the day. It can come and go randomly like that. Since your wrist contains all the nerves and vessles that branch out into your hand, sometimes your whole hand can hurt and or tingle if you have this condition.

Another thing might be to have your circulatory system checked to rule out heart attack.