I think 9:47 would be better.
You should be getting about 9 hours of sleep at that age. So if you need to get up at 7:30 am, It is a good bedtime.
Cheese isn't bad for your teeth. -rda
I'm doing it for my biology project too and I've found that sweets chocolate and sugary things are and also acids and juices, they cause plaque and decay which errodes (cuts) into the enamel(a hard protection on your teeth)on your teeth and causes cavities and tooth ache as the nerves in your teeth are exposed.