Mirtazapine
"I am a leukemia patient and after all the meds I've been on and still are on sleep can be a challenge to say the least. I was originally put on 15 mg of Remeron at 
bedtime to help gain weight for Bone marrow transplantation  (BMT) but found it helpful for sleep as well. After taking it for 2 years it started not to work as well, so now I take 1mg Ativan and 15 mg Remeron for sleep. It takes about 2-3 hours to kick in but I sleep an average of 8-9 hours a night. Cup of coffee after breakfast and I'm not groggy. Hope this somehow helps."