I'd be very dubious about sleep data from a Fitbit. Devices like this one monitor how much someone moves. People in even a deep sleep can move a lot, so the watch can provide misleading information. Some watches claim to use heart rate to measure deep sleep, but they aren't necessarily accurate, and they aren't marketed to children (who have faster resting heart rates than adults, especially ages ten and under).
If you're very concerned about your DD's sleeping habits, you might want to talk to her pediatrician, who in turn might order a sleep study if something seems amiss.
