I honestly couldn't tell you... unless you somehow pinched a nerve, have low blood circulation or slept on it for way too long... I have no answer for you. It'd be best to see a doctor if it persists or spreads!

I also have had numbness in my left thumb-kind of the outside edge of my hand from the wrist and including the outside edge of my pointer finger. This is new since yesterday with no apparent injury. Any ideas would be welcome.

it is peripheral neropathy can be caused by many things, see a doctor usually its caused by damage to the median nerve be it viral, poison, blood leaking into the nerve, the list just goes on but some can be serious problems go to a doctor