Cortisol is a stress hormone. Reduce stress.
Get at least eight hours of sleep without any screen time two hours before you try to go to bed.
Don't try to multi-task, drop commitments that don't have an emotional investment for you (or you need to do legally / pay the bills).
Set a budget and pay down debt so you don't worry about it in the first place. I recommend Dave Ramsey or Suze Orman on that account.
Don't check messages and social media constantly.