Sometimes weed helps me sleep, but sometimes it keeps me awake all night, and I have no idea why

While my cannabis usage isn't strictly medicinal, I appreciate its ability to help with falling asleep, something that I've periodically had issues with for most of my life. However, I've been having trouble with inconsistency in its effects on me - sometimes I can go right to sleep, but occasionally it keeps me awake long into the night, even after its effects should've worn off.

I typically use indica hybrid live resin vape cartridges (whole-plant smoke is harsher on my lungs, and my wife doesn't like the smell of it anyway), and my usage is pretty moderate, typically 2-3 times a week in the evenings. Originally, I had believed the issue to be related to the strain, and I think it is, to some extent - some carts I've tried seem to work better than others, but even within the same strains I've had mixed effects.

For example, last night, I started a little before 8 PM with a cart I got a few weeks ago that didn't have the strongest effects on drowsiness of anything that I've tried, but also hadn't given me any trouble up to this point. I tapered off after 9, only having a couple of smaller pulls before 10, where I stopped, and I went to bed at 11. I've been working off of a hypothesis that it's easier to sleep after the peak of a high has passed, which I haven't been able to really prove one way or the other, but it... might help?

At any rate, I felt some kind of residual effect of the high that just... prevented my brain from fully disengaging and falling asleep, which lasted past 5 AM, far longer than I feel like it should've lingered. It didn't feel unpleasant or anything, and I went a lot longer before checking the time and getting worried about it than I would've normally. Still, I'm fairly certain I didn't fall asleep until some time around 5:30ish, and I sure felt sleep-deprived when my alarm went off this morning.

I've had similar experiences before with different strains, which I've previously attributed to either the strain itself or the timing of its use. After last night, I'm starting to get pretty frustrated that I can't figure out why it's such a crapshoot sometimes.

I know an internet forum is not a place for definitive medical advice, but the last time I talked to a doctor about it, it wasn't particularly enlightening, and the people at my dispensary haven't been able to give much advice either, beyond "use indica strains." If nothing else, I'm at least trying to see if I can get any ideas or leads on things to look into and research further. Any advice?