Numb hands?

Is this normal?
My hands seem to just go numb. I have no idea why and I've never had this
before. It's always when I wake up after sleeping, though. It's happened a
number of times in the last 2 or so weeks...
I'm just asking if it's something mainly because I woke up this morning when
the alarm went off - or I sort of woke up, enough to try and roll around to
turn the alarm clock off and bang... both hands were pins and needles like
they were sleeping. They just wouldn't move. It was from about my wrists
down on both hands.
No, I was not sleeping on my hands or arms - they were on top of me.
Then again this afternoon - I fell asleep on the couch. I woke up not long
ago and the same thing... My hands were numb, wouldn't move and were
"sleeping" again.
Up until today, I would guess this has happened only when I wake up in the
morning maybe every couple of days. Now it was twice in the same day.
It takes a few minutes for me to be able to get some feeling back in them,
then they're fine. Again, I'm definitely not sleeping on them to stop
circulation or anything like that.
Is this normal? Baby #5 and I believe I will be 27 weeks tomorrow and I've
never had this ever before (pregnant or not)