A lot of people immediately blame Modvigil/Modawake when they feel side effects, but often it’s the overall routine that’s the real factor—especially hydration, food, and caffeine.

In your case, it’s pretty clear:
When you were taking it with coffee, on an empty stomach, and barely drinking water, the side effects like dry mouth, headaches, and irritability were almost expected.

But when you adjusted things—proper breakfast, good hydration, and earlier timing—the experience became much smoother and the focus actually became useful instead of stressful.

It doesn’t necessarily mean the medication “changed,” but rather your body was in a much more stable state to handle it.

And honestly, that’s one of the biggest lessons with stimulants/nootropic-type substances: hydration, sleep, and food can easily make or break the experience.

Still, like you noticed, timing and sleep disruption can remain sensitive, so it’s best treated more like a tool rather than something to rely on daily.