Dexamfetamine + zero sleep = fluent speech and hyperfocus? (Instead

When I'm well-rested and take my dexamphetamine, I often find myself searching for words and mentally shifting gears a bit sluggishly. But if I've barely or not slept at all for a night and take it the next morning, I suddenly navigate conversations much more smoothly and sharply socially, and my brain functions bizarrely sharply. Other people I talk to also notice this. How does this work neurobiologically? Why does that lack of sleep actually counteract the sluggishness (the 'searching for words') caused by the medication? Does anyone have experience with this?