We should sleep 9 and a half hours a night, but a large part of the population suffers from insomnia. Because?
Our animal cousins, philologically closest to us, sleep around 9 and a half hours out of 24. Many monkeys are hardly ever awake: they sleep for 17 hours a day. David Samson calls this discrepancy the human sleep paradox . “How is it possible that we sleep the least of all primates?” Samson wondered. Also supporting this oddity is the fact that a predictive model of primate sleep, based on factors such as body mass, brain size and diet, concluded that humans should be sleeping 9.5 hours a day. not seven.
The reasons for our strange sleeping habits are still a matter of debate, but can probably be traced to the history of our evolution .
Millions of years ago, our ancestors lived and probably slept in trees. Today’s chimpanzees and other great apes still sleep in beds or platforms built in tall shrubbery. The common point is that they sleep surrounded by other animals, often noisy.
David Samson, of the University of Toronto, argues that our sleep problems could have to do with stress or out of phase circadian rhythms. When we struggle to fall asleep, we may have an imbalance between how we evolved and how we live now. “We are basically isolated and this could affect our sleep,” explains Samson.
At this point we also came to the conclusion that insomnia is, in reality, a hypervigilance , an evolutionary superpower. “It was probably an adaptive behavior when our ancestors slept in the savannah.”
“The so-called social sleep hypotheses propose that the current characteristics of human sleep have emerged due to the construction of social and technological niches. In particular, sleeping places function as a type of social shelter. Short, high-quality, flexible-time sleep likely arose as a response to predation risks during terrestrial sleep. This practice may have been a necessary pre-adaptation for migration from Africa and for survival in ecological niches penetrating latitudes with the greatest seasonal variations in light and temperature on the planet,” writes Simon in his study.
- The Human Sleep Paradox: The Unexpected Sleeping Habits of Homo sapiens. (annualreviews.org)