Heart rate increasing rapidly

Kori • 21yrs old & expecting 🍼👶🏾 my first child with the love of my life ⚓️❤️
Every time I lay down for bed my heart races just as fast as the little boy's that I'm carrying. (22 weeks today) I'm not sure if it's stress or from my body trying to settle itself down. I have been stressed out a lot though. I have tried relaxation methods but still nothing seems to help. I don't want my stress getting to the baby even though I know that's easier said than done since he is in my body. I know I need to relax because going into preterm labor and giving birth before 36 weeks at least is definitely not the goal of this pregnancy. 
Any advice?