I take a bunch of things at night to try to get to sleep. In fact I'm glad you brought the subject up because I've been staying up way too late and now I realize I used to take 5mg melatonin an hour before bedtime to encourage me to want to go to bed, and I haven't been doing that for a while.
The plain melatonin is what I like an hour before bedtime, then when I'm really ready to sleep I take the melatonin that includes l-theanine. I buy it from Amazon.
Some of the melatonin types sold in the grocery store have different added ingredients and didn't work for me.
Also, I found I don't like taking L-theanine separately because the higher dose is unpleasant to me. But the tiny amount in the 'Calm Sleep' variety of melatonin is just perfect to cause me to have lots of dreams, I even keep a spare one next to the bed so that if I wake up too early I can take it and go back to sleep and have lots of fun dreams (no, not that kind).
I also take a 'sleep-aid' pill from Walmart that I think is a half-dose of benedryl. It used to zonk me out but I think I've adapted to it, I should probably stop taking it and save it for special times.
Another thing that helps me get to sleep is listening to lectures on Youtube as I go to sleep. They have to be just right, not too interesting but not too boring. And I have to like the lecturer's voice and style. Also I have to make sure I don't have auto-play on because it will drive me nuts if the lecture doesn't stop soon after I fall asleep.
Sapolsky lectures usually work for me (but NOT the one about zebras not getting ulcers!). Once I bought a lecture about classical music because I figured the music would be soporific and the lecture would be boring, but instead the lecture caused me to laugh so much it woke me all up. You wouldn't believe how impassioned the lecturer was about some famous piece of music whose composer purposely used a b-sharp where everyone knew the note should have been a b-flat (or some such thing like that).