You can safely take unisom (an over the counter sleep med) but it can't be the capsule kind. They also say it works for some women for nausea. My obgyn told me when my morning sickness was unbearable.
Wear yourself out, when I have trouble sleeping I usually go home after work and take a long walk then clean my house and if it's not to late maybe take another walk. I pretty much keep moving until like 8:00 which by that time I wore myself out and get a good night sleep. Plus it's good for the baby to get your heart rate up, the faster your heart rate the more blood pumping which is great for the baby. Just don't over do it. Good luck and congrats!
On occasion you can try benadryl or tylenol PM, but avoid medicine in general when you can. My sleeping was so bad that after the first trimester I was given ambien. I took it sparingly though.