My arms and legs often get numb if i keep them in the same position for "too long" it specially happens while sleeping, what can i do to prevent this?

? Pressure on nerves: It could be caused by pressure on nerves by sitting in one position for too long or sitting in an awkward position this is usually a temporary condition that goes away. However, it could also indicate that something is wrong.I would consider seeing the doctor.

Pinched nerves: It seems that your nerves get pinched in neck as well as low back in flat sleep posture. This also indicates that your outlets for the nerves could be narrow in neck and back. See a neurologist and you may need MRI scan of neck and low back as well as ncv/emg.