Hey C.,
I would think waking her earlier or having her lay in bed relaxed at night should help. We have to train our bodies.
However in your case, I would discuss the medication regimen with your doctor. My concern is that your child is taking Vyvanse and probably not being treated by the appropriate professional. I am guessing your daughter was prescribed the medication by a pediatrician. And that she probably never had psychological testing by a child psychologist who admisters several tools of testing to give the accurate diagnosis. Once a diagnosis is made, that paperwork is taken to a child psychiatrist who knows thier Psychotropic Medications and knows the doses used for children as most meds are not even approved for use in children.
To add to all that, my concern is warranted by the fact that you noted your daughter will be returning to school soon. And that this is summer break. Most pediatric/child psychiatrist wean from ADHD medications at beginning of summer and then build back to dose for school. It is a needed break, but also allows the child to continue with a normal growth pattern. Something your pediatrician is not likely to know about.
And to answer your original question, without knowing when the Vyvanse dose is being given, I am guessing the dose needs to be earlier in the morning, and if there is a 2nd dose, then moving both doses up, or halfing the second dose, so that she can fall asleep earlier. But of course talk to her doctor before making any changes yourself.
Hope this helps,
-MB