not eating a lot

So I'm 18wks and I think I'm starting to get insomnia or something because I can't for the life of me sleep at night. I can sleep most of the day but it worries be bc I'm not eating a lot, I try to but I'm having really bad food aversions and want nothing healthy except squash. I'm just so worried that it'll affect my baby. I know that I should eat healthier but what's the point if I'll just throw it up. Any advice on how I can sleep better? Is there a pill that pregnant women can take to help them sleep?