Throwing in a bit more with YMMV...

Xmg of melatonin is hard to measure, because there's apparently not great accuracy in most OTC pills. And... it may take you days to confirm if a specific pill is 'working' well or not. If/when you find a combination, buy a bunch to have on hand.

I recently received the book "why we sleep" and it discussed melatonin's process. If "1 hour before bed" works for you, that's good, but it never did for me. ~3 hrs did. Or... at least 2-3 hours at this time of the year. My routine has been taking a melatonin between 6 and 7ish, and by 10 I'm typically quite 'ready' for sleep, and it's usually a fast process. It doesn't seem like it in the moment, but my wife has noticed I'm "out like a light" (which I think is more just in comparison to months ago).

You can buy liquid fast acting melatonin. I take a pipette 1 hour before bed time and by the time I got the pillow, I am so sleepy I fall asleep instantly and do not wake up during the night.

I would suggest you also look at the criticisms about the book you mentioned, Why We Sleep. I'd take the book's conclusions with caution.

Have read some - it's not a panacea for sure. It did recently renew some interest in the subject for me, but yes, take it with some caution, certainly. It did make me re-evaluate some of the things I was doing re: sleep, and I've generally had somewhat better results since making adjustments.

I bet you could quarter your melatonin dose and still get the effects. Do some reading, but 3mg (although a common OTC dosage) is pretty high.