I have been reading of how humans used to have much different circadian rhythms in pre industrial times. I find this idea of four hours of sleep, then one or two hours in a quiet wakefulness, then 4 hours sleep very intriguing. It wasn't until artificial lighting became prevalent that we went to bed late and slept through the night. I may have to reawaken the olde tradition of a midnight smoke and quiet but blissful meditation.
This is the full paper.
This is the full paper.