Get a boring book and read it in bed. Math and science textbooks from school are perfect for this. Any sciency book will do. The more formulas,references, and definitions, the better. Works every time, guaranteed. Just keep at it until your eyes start crossing the words on the page, then shut the lights and knock out. Be careful, this is a powerful method. I often fall asleep with the book still in the bed so soft-cover would be ideal.
Getting good sun during the day and keeping lights very low for an hour before bed is helpful too. TV, tablets, and phones before bed are too bright. At least for me, cell phone radiation has the effect of making me drowsy during the day and keeping me up or waking me up at night. So try turning off all your phones, wifi routers, etc. an hour before bed. It should help.
