Doxylamine
"I have had my battles with the inability to stay asleep of 10 or 12 years.  Go to sleep just fine but wake up at the 5 hour interval and cannot get back to sleep.  I would get very tired during the day - it was terrible.  I heard of this at Costco and started taking 1/2 tab per night.  Bang!  8 hours of great sleep!!!  I don't have drowsiness and feel like I used to.  It doesn't know me out - I can wake up to go to the bathroom. ( I am over 55 and a guy) but I go right back to sleep.  Love this stuff.  I hope it's not bad for ya because I need  good sleep."