Can't sleep

I'm only 5 weeks pregnant but I can't sleep. It's hard to fall asleep, and then as soon as I wake up (no matter how early it is), I can't go back to sleep! I don't know if this is an actual pregnant symptom, or if I'm just so excited my brain won't settle down. Has anyone had this problem and what did you do about it? I'm worried about getting enough sleep for my growing babe!