So, part of my thinking in the combination that I suggested is that the large dose of melatonin should help to set your circadian clock a little...and with the success of the other ingredients, that reset will become reinforced. With continued use, you will see that you normally start getting more tired around the time you normally take it, even without the pill.
The melatonin dose is high in that formula I created because, well, it serves other potential benefits regarding insulin resistance, fat loss, and general health.
Smaller doses (sub 1 mg) may actually have a more direct impact on sleep - I've taken 3 mg and not noticed much but 1 mg or even less can have me asleep fast. I don't fully understand this but can oversimplify and say that falling melatonin levels play part in our process for waking up - so having a small bump should make you sleepy, but then you wake up in the middle of the night potentially if your body isn't producing enough.
The GABA and all of the other nutrients also have some pretty interesting health benefits, particularly around diabetes.
It's not magic, but it's a formula that I think actually gets better with regular use, while a lot of the marketed formulas hit harder in a one-off situation, but can't be used forever or every night. Not against that - I have times when I need that extra kick. But this formula will likely leave you groggy at first for a few days, then after a few days you will start sleeping maybe an extra hour a night for a couple weeks, and then after that you will start noticing you need less sleep altogether. At least that has been my experience and the experience of a few people I've given it to.