For our kids (youngest was 5 during our last trip) we made sure they had 8 hours sleep minimum. After a busy park day it took them seconds to fall asleep,too.
So, it depends on what time you’d get back to the room, which can vary a lot depending on showtime and resort you are at.
Also, rope drop depends on park opening time, what you plan on doing (FOP requires and earlier arrival time than Frontierland).
Also, transport time to park in the morning depends on resort/park combination.
And, how long it takes you to get ready, and what you are doing for breakfast (full meal or quick snack with full meal after rope drop rides).
Conclusion: it can be done with careful planning.