I'm not a doctor, but will try to think of a few suggestions.
Look at your normal sleep position. Have a friend or roommate check on you during the night... you might be moving into a position that cuts off the circulation to your arms a little, like on you side with 1 arm under your body.. both arms under your pillow.. arms crossed... etc.
When you wake up in the morning, do some light stretching and moving around. I suggest the sun salutation exercise.. I've done this almost every morning for about 8 years:
as for ab exercises, I don't like to do the insane high rep thing for them... I do low reps with high resistance.... like these:
gets your abs burning and rebuilding without investing hours and hours on them
best advice is to talk to a doctor about it the circulation thing though, could be indicitive of larger problems.