8 years old is around the time of another growth spurt. There is a time then, and again in mid adolescence, where their stomachs cant get enough nourishment in at one time, and they need more meals, every 4 hours. Their stomachs are not big enough to contain the nourishment they need. This sounds like it might be one of those times. Does she have a good supper before bedtime as well as her tea earlier? that can help.
Mind you, as she is targeting sweet stuff, it could be that something is worrying her or has changed in her life.