Sleep

This is such a massively broad topic but I ran across a review of the literature on why we sleep in PLoS Biology. Check out the above table of the leading reasons why we need to sleep and the pros and cons of that arguement. Previously I had thought that it known that sleep was necessary for learning and thus just plain necessary, but it turns out that it is just one of three leading theories. The most convincing to me according to the review is the theory that we require sleep to restore some key macromolecules. The article also contains many other interesting aspects of sleep research including some conjecture on why evolution favoured sleep as such a prevalent behavior, but I didn't understand much of it.