[madmmac]

Is it both hands or just one at a time when it occurs?

Laying on your side, on your shoulder can impinge the medial nerve which can cause the numbness, although it would only affect the arm/shoulder you are laying on.

Single hand onset may be an indication of impending carpal tunnel problems. Although I imagine it could occur at the same time in both hands, only I would not think it would be as normal as the single onset.

Good luck,