The above link talks about how light and culture affects sleep, she even mentions that a natural sleep cycle seems to have people falling asleep around 8pm until 12pm at which they awake and maintain a 2 hour, pseudo-meditative state, before falling asleep again until sunrise. She claims that people who try this type of sleep remark at actually feeling awake for the first time!

I definitely would like to find more info about this. Any comments or ideas?