Some links I came across with a thorough, well researched view of sleep. Two articles, with key excerpts:
“…Myth: Since we feel rested after sleep, sleep must be for resting. Ask anyone, even a student of medicine: What is the role of sleep? Nearly everyone will tell you: Sleep is for rest. Fact: Sleep is for optimizing the structure of memories. If it was for rest or energy saving, we would cover the saving by consuming just one apple per night. To effectively encode memories, mammals, birds and even reptiles need to turn off the thinking and do some housekeeping in their brains. This is vital for survival. This is why the evolution produced a defense mechanisms against skipping sleep. If we do not get sleep, we feel miserable. We are not actually as wasted as we feel, the damage can be quickly repaired by getting a good night sleep. It is our brain dishing punishment for not sticking to the rules of intelligent life-form: let the memory do restructuring in its programmed time.”
“It appears that polyphasic sleep encounters the precisely same problems as seen in jet lag or shift-work. Human body clock is not adapted to sleeping in patterns other than monophasic or biphasic sleep. In other words, the only known healthy alternatives are: (1) a single 6-8 hours sleep block in the night, or (2) a night sleep of 5-7 hours combined with a 15-90 min. siesta nap. Those numbers differ substantially across the population and there is no single recommended dose of sleep for everyone.”
The site these articles came from, www.supermemo.com, is called “Super Memory: Forget About Forgetting”. I’ll be looking more into it soon.