A 16 year old girl will not die suddenly if she sleeps only 7 hours for a long period of time.
Sudden death has nothing to do with the length of sleep. Sudden death refers to the appearance of a healthy person, suddenly occurring pathological death, related to the original serious underlying diseases, usually due to overwork, infection, emotional overstimulation, serious traumatic events related to the length of sleep has nothing to do with.
Adolescent sleep time in 8 hours or so is appropriate, sleep time 7 hours will be slightly shorter, you can appropriately increase the sleep time, pay attention to rest, usually pay more attention to living habits, aerobic exercise, enhance physical fitness, maintain an optimistic mood.
If the body is not comfortable should be timely consultation.