My daughter started falling asleep about age 9 unless she is performing physical activities, like playing. sleep study shows no abnormalities. ?

DOES: An interesting disorder of sleep involves the disorder of excessive somnolence (does). It can be a normal variant of childhood. Some children need more sleep, but are otherwise very active and appropriate. Some causes can be lack of night time sleep, medications, illness, boredom, etc. A thorough medical evaluation would be appropriate.