Doxylamine
"The Unisom Tabs 25 MG does not work for me even if I take 2 tablets.  I was diagnosed with Sleep Apnea about 5 years ago and have gone from taking the  of the "Z" pill (6 MG) to taking the extended release "Z" pill (12.5 MG).  Decided to try to wean myself off for the past week by taking only half a dose of the "Z" pill and amazing that worked.  Now, trying the Unisom Tabs and trying to give it a week before I refill the "Z" tabs.  As I sit here, I am tired on night 2, but still don't think I am tired enough to fall asleep."