Amitriptyline
"I have taken this medication during certain times in my life due to events and change of time zones for long periods of time when my sleep pattern is broken.  It is great.  I have been able to stay at 25 mg without increase for more than a year and work myself off when fully recovered.  Be prepared to wait for it to kick in up to 2 weeks after starting it.  It needs to fully get into your system.  Everyones body is different.  Recently I tried zolpidem for a more immediate sleep and found I could only get 4 hours a night. I read about the addiction of it and possible rebound insomnia after weaning yourself off.  I am going back to that old model medicine, Amitriiptyline.  It is great and I get back to a 7-8 hour sleep pattern."