Scientists recently confirmed what parents have long suspected: kids who run around and play hard have less trouble falling asleep. The study of almost 600 seven year olds used activity-measuring devices worn on the children’s waists. Those who had an hour of vigorous activity fell asleep 6 minutes faster than average after they went to bed.
[Archives of Disease in Childhood, Sept., 2009]
http://adc.bmj.com/cgi/content/abstract/94/9/686