I rarely dream either way (unless I start focusing on that specifically, then my recall will improve quickly). When I was younger and would go to bed severely stoned I would wake up groggy and lethargic - clearly not optimal sleep. On 3-4% THC I usually wake up spontaneously and feel well rested. It mostly just helps me fall asleep and stay asleep. YMMV obviously.

It’s a pretty low dose, doesn’t exactly send me into space—heavy users might need 10x or more that dose to even feel it—just enough to make my brain shut up so I can fall asleep. I think a lot of folks who have a bad time when they try it start at far too high a dose (I wouldn’t even start at 5mg, maybe shoot for like 2), I also don’t much enjoy being properly high, anything past what you’d call a heavyish buzz I find unpleasant (and my standard nighttime dose doesn’t even quite get me to the heavier end of a buzz, that’s more the 7-10mg range for me, though I’d caution that some gummies seem more potent and some nominal-5s do get me closer to that than others)

I dunno about sleep quality effects, but it’s definitely better than even a couple beers (for me, these days) and it’s way better than lying awake until 3am… for the third night in a row. For most of the night it should be mostly worn-off, again, I’m not taking a ton and it takes longer to work through you in edible form than smoking, but we’re still talking less than half the night, especially as I usually time it so it hits just a little while before bed (I don’t want to get in bed without it having hit yet).

I don’t remember having had dreams most nights anyway, so I don’t know about that. Even with some help I’m typically a bit under the low side of the amount of sleep I ought to be getting, over a week. Lucky if I break the eight-hour mark two days of the seven, usually in the 6.5-7.5 range the rest (I don’t take a gummy every single night, either, gotta keep that tolerance at bay). I think I dream (or, at least, remember it) more when I get the rare series of several days of 8+ hours, but I don’t track it so can’t say for sure, and yeah, no idea the effect of weed on that.

I can vouch that at my dose level I get way better sleep than I did the one time I tried a prescription sleep aid, which was Lunesta. If I didn’t get a solid 9 hours on that I’d wake up feeling hung-over, weed doesn’t give me extra trouble like that if I fail to get a full 8+ hours. Hell, even a “good” night on lunesta didn’t leave me feeling awesome in the morning. Other downsides: it mixes worse with other things, had a glass of wine with dinner? Better think twice about the lunesta, at least according to the label. On some decongestant medicine (in addition to antibiotics) for a sinus infection, and the sinus infection is wrecking your ability to sleep so you could really use it? Might not be able to take it with the other stuff. Weed’s so much better for those cases especially, bump the dose slightly and nothing short of something that’s gonna hospitalize me will be able to keep me from sleeping, and it famously doesn’t interact badly with very many other drugs, so it removes the very worst thing about most common illnesses like that (for me, anyway) which is the extreme sleep disruption.