You — a lark or an owl? Blame it on ancestors!
It seems that the natural tendency to stay up past midnight — or, conversely, to Wake up early in the morning — we owe it to our ancestors. So why do some of us prefer to sleep longer in the morning, and someone, on the contrary, inevitably tends to sleep long before midnight?
As noted by anthropologists, a variety of modes of sleep and wakefulness in people living together was very important to primitive communities of hunters and gatherers, as there was need to have someone constantly standing guard against predators.
Researchers observed the indigenous people of the hadza, still living primitive communal system on the shores of lake Eyasi in Northern Tanzania.
A 20-day study of the life of the tribe it became clear that for nearly all this time at least some of his representatives sure were awake.
“Of the approximately 200 hours spent on surveillance, all the tribesmen slept only once for 18 minutes,” said study leader David Samson from the University of Toronto. Thus, sleeping in turn people actually followed each other, and the whole tribe as a whole was in a dream only 0.15% of the total time.
On average at any time of the night at the same time bokstavelig eight adult members of the tribe — that is, 40% of the total adult inhabitants of the Parking lot. We absolutely struck by the almost complete lack of synchrony of the sleep of this group nudedavid Sumerological research
Previous studies have shown that about 40-70% of the functioning of the circadian rhythms of the person (what is called the biological clock) is determined by genetics. For the rest of the answer environment and age, and as they grow older the influence of the latter factor increases.