We all do it! As we get older it becomes more necessary. In that way, the elders are like babies they need extra sleep time. I'm not sure the science behind it but I figure we just need to rest more because we have so much in our minds we need to work through except, unlike a baby we are remembering not learning.
I'm doing this Monday morning after a very busy week-end so I figure a couple of info graphs will be able to explain a lot more than I can.