If you have repeated episodes of an arm or hand falling asleep make sure you route out the problem and correct it, otherwise you might end up with a more chronically pinched/damaged nerve that you will have to rehabilitate. One common problem is sleeping with your elbow tightly bent and pinching the ulnar nerve. This is common because people do it in addition to bending their elbow deeply during the day as they use their phone for extended periods. If you see this as a problem and aren't sure how to stop it you can get an inexpensive cuff, stiff but soft, to wear on your elbow to "remind" it not to over-bend.
IMHO this is a nerve issue, not a circulation problem. Your oximeter should provide valid data.
if you can't decide then you don't have enough data.