Our sleeping patterns are largely a function of our daily activity, which for most of us revolves around our and our family's work/school schedule.
There are variations such as the afternoon siesta, which is the norm in some countries, as well more polyphasic sleeping (multiple short sleeps during a 24-hour period).
In terms of health there is clinical evidence that shift workers - who are chronically at odds with their natural sleeping requirements - are at increased risk of cardiovascular disease and cancer.
However, this may not be the case for everyone as there is evidence of genetic polymorphisms associated with preference for night vs day in terms of peak cognitive performance.
'Social jetlag' is a term coined to describe the disparity between our obligations to society (e.g our employer) and the needs of our biological clock.
Clearly, modern sleeping habits are not those of our ancestors and there may be a metabolic and health price to pay in order to conform.
How can sleeping be made to be more paleo?
I positively, absolutely confirm that sleep quality affects cardiovascular health. If my sleep is bad, late, or not enough, I can find myself bending over after like running up the stairs, and my resting pulse will be about 10 or 15 beats per minute higher. If my sleep is good, early, and enough, then I can run at least 24 minutes straight (even while fasting), and my resting pulse will be down in the middle 50's, which is my usual pulse.
I gave Harry Banaharis a +1 and clicked his star for this one for bring up the connection between sleep quality and cardiovascular health.
Although the connection between sleep and cardio health is strange, for me it is a FACT, and it is an immediate FACT. I don't have to wait for scientific studies to confirm it. The only explanation I can think of is that nerves control the endothelial muscles that control the width of the arteries. If someone else as another or better explanation, I invite you to post it.
I go to bed early every night and wake with the sun as much as possible. In winter it is harder because I have to wake in the dark. I somehow manage without the use of an alarm clock and going to bed by 9pm.
I disagree with those who say your sleeping environment must be pitch dark for proper sleep. I slept in the wilderness for 6 months. There's about a week of each month when sleep is difficult, even in deep forest, because of the moon. There's another week or so where it's a little less difficult because the moon is either not there or only affects a small portion of the night. I learned that perfect sleep every night is not important and not even natural.