[StevenWaterman]

Essentially the idea is that there is an "optimal" amount of alertness (inverted U curve). People with ADHD start below the optimal point, and stimulants move them up towards the optimal point. People without ADHD are typically closer to the optimal point, and stimulants move them past it.

Someone with ADHD taking a large dose will therefore feel the same as someone without ADHD taking a small(er) dose.

Methylphenidate improves sleep in people with ADHD: https://pmc.ncbi.nlm.nih.gov/articles/PMC2276739/

> Compared to [non-adhd] controls untreated [adhd] patients showed increased nocturnal activity, reduced sleep efficiency, more nocturnal awakenings and reduced percentage of REM sleep. Treatment [of those with adhd] with methylphenidate resulted in increased sleep efficiency as well as a subjective feeling of improved restorative value of sleep.

I can't find a corresponding paper studying the effect of stimulants on sleep in healthy adults. I would assume it hasn't been studied because it's common knowledge and it's not worth the risk of making healthy people take stimulants. I also don't think that's the part you were disputing.