A new study claims that the difference in sleeping hours between the older population and the younger one may be more than just an advancement in age. It could be an evolutionary adaptation to the environment which served as a survival tool for our ancestors.
This is quite in contrast with previous studies which tied bad or less sleep to issues such as Alzheimer’s Disease or to spending too much time with technology. Other researchers also looked at the long term effects of a lack of sleep, but this new study is trying to find a possible cause.
Different Sleeping Hours Ensured That at Least One Person Was Awake
The new study was conducted by analyzing the sleeping patterns of the Hadza people which live in northern Tanzania. These are a hunter-gatherer tribe which still live similarly to our earlier ancestors even in the modern day.
Researchers monitored them over a period of three weeks and analyzed their sleep customs and patterns. The Hadza were noted to be living and sleeping in groups of some 20 to 30 people. During the day, each goes their separate way, typically reuniting only in the evening as they go to sleep.
The study tracked the sleeping patterns of 33 healthy Hadza, both women and men. These were asked to wear small, watch-like devices which helped record their nighttime movements, for 20 days.
There were more than 220 hours of sleep recorded. However, during them, there were only 18 minutes in which all of the adults were simultaneously asleep. On median, over a third of the group was either very lightly dozing or even alert at any given time.
Sleeping Hours, a Vestige of the Human Past?
The researchers were surprised by the minimal value. They also claim that it might indicate that flexibility and variation are natural properties of the human sleep. Previous studies revealed this same effect in mice, birds, and other animals. However, this is the first research to show it in humans.
The study authors claim that the different sleeping patterns of the old, when compared to the young, could be an evolutionary adaptation. One that helped them survive in past ages when our ancestors slept in mixed-age groups.
“Maybe some of the medical issues we have today could be explained not as disorders, but as a relic of an evolutionary past in which they were beneficial,” states Charlie Nunn, referring to older people’s issue of waking up early and being unable to go back to sleep.
Nunn is a study co-author and a Duke University professor of evolutionary anthropology. Research results are available in the Proceedings of the Royal Society B.
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