Sleeper by Katherine Rhodes

Dr. Wren Warner—successful, respected, and hard-working—doesn’t have time for problems. She has patients who count on her.
All of her problems lie in sleep.
As in, she can’t. When she does, she is haunted by memories of fire and swords. It’s starting to interfere with her work and she’s desperate for answers.
One person may be able to help.
Dr. Fischer Skillman is the best neurologist on the east coast. Not only does he know his way around a brain, but he knows dream disorders better than anyone. Things don’t start off well when he pisses Wren off before their first consult.
But then, they touch.
Wren and Fischer share a vision neither of them can explain–the first of many. Wren is tired and scared, while Fischer doesn’t want to investigate the reasons. When Wren is called in to help the children rescued from a sex trafficking ring, she needs Fischer’s help, but he refuses to budge. It’s not his job.
Wren and Fischer are pulled into a mystery when Elutheria—one of the rescued girls—proves to be nothing like the others. They find themselves in the center of things that defy understanding—but they need to understand, to save Ellie.
“The soul of the sluggard
desireth, and hath nothing:
but the soul of the diligent
shall be made fat.”
–Proverbs 13:4