I'm not sure if I have carpal tunnel officially or not,but my symptoms are similar. I narrowed it down to only a couple of things because I don't have circulation problems really but I think I may have symptoms of diabetes. But that still probably wouldn't cause the problem I've been having recently
I first started having this back around 1998 when I used to work in a factory doing repetetive packing work. I'd wake up sometimes with only my right arm in pain and numbness. I figured it was some kind of compacted nerve or something. Since then it hasn't really flared up until recently when I started work back in shipping and now more often I wake up with the numbness again.
I should mention I don't have any regular medical insurance so I have to pretty much self-diagnose for the time being.

NG-

For a Diabetes confirmation, you could go to your MD and have the Hemoglobin HbA1c test performed. This will give you an agregate number to give you your blood sugar average over the previous 3 months. I've used a home version of the test (available for under 20 dollars at drugstore chains) which matched the doctor's lab results.

Unfortunately, checking for where your numbness comes from can be way more expensive. For arm numbness, I would lean toward a possible herniated disc in your neck. If you start to experience muscle weakness, you need to get it checked out.

wb