i've never had a problem with staying or even falling asleep, instead my issue is *wanting* to go to bed and getting myself there. adhd, executive dysfunctoning/akrasia, screens, chores i procrastinated all evening, etc, all give me too many things to do at night instead of tucking myself into bed. i basically don't feel tired at all until i lay down. i don't notice i'm mentally wiped until i start bottomfragging in a video game at 2 am.
i've taken melatonin (and magnesium) for a long time, but only in the past few months i started taking it like 3 hours before bed, after reading scott alexander's psychiatry website, instead of right beforehand.
i also happen to have been recently RXd a drug called guanfacine which dampens sympathetic activity (think fight-or-flight) and when i take it with the above pills, i finally *feel* tired at 10 pm. my body is heavy and slow and my brain starts craving being turned off. it's remarkable. there's something about *feeling* tired that is humbling and makes me feel human. weird!
BJ et all aren't joking when they say the biggest performance enhancer is sleep and especially regularity. i would rather sleep 6 hours and wake up at my normal time, than slide my schedule around and hit 8 and sleep in. but when i hit 8 on my usual schedule it's like i have superpowers. i don't make gains at the gym unless i sleep well. and it's such a funny thing to say out loud, but i don't need coffee when i'm rested. when i'm rested and take a coffee, it feels like i just drank 3 coffees and i'm ODing on top of my natural alertness.