What is the connection between sleep requirement and age?
I believe the current theory is that it is related to cell loss in the intermediate nucleus of the human hypothalamus. They have shown sleep disruptions due to lesions of the hypothalamic ventrolateral preoptic nucleus in rodents, and found that the intermediate nucleus in humans is homologous and shows a reduction in size in older adults that is correlated with sleep disruptions. http://brain.oxfordjournals.org/content/137/10/2847