C.S.
You don't mention her age, but if she doesn't nap, perhaps at least have her do quiet time for an hour or so. This may give her the down time she needs. I begin quiet time with reading then my two play in their rooms. It usually does the trick. If not for my son, he will take a 'power nap" at about 5:30 for 30 minutes & be right as rain. hope this helps.