My otherwise healthy, sporty, slim, laid back dd is coming home from school and going straight to bed for 3 hours. Need to wake her for tea. Then she soon goes back to bed for her usual 10+ hours at night. Says she's not unhappy or unwell, just terribly tired. She has had a couple of GCSE exams in the last 2 weeks but not particularly phased by exams usually, very bright A grade student, copes with pressure. What am I to think? Ignore it or go to the doc?