I also came across an interesting article in the internet that sleep
deprivation had been used to treat depression in the past and now again there are some
experiments on this. From what I read, some depressed people are very lethargic and sleep too much, and when you deprive them from sleep , some of them actually become more energetic. Interesting.
Anyway coming back to your granddaughter, is she going through any hormonal changes, that could possibly cause sleep loss.