In the study, "Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies," Yetish et al (2015) aimed to investigate the natural sleep patterns of pre-industrial societies and how they differ from those of industrial societies. The study was conducted on three pre-industrial societies, the Hadza of Tanzania, the Tsimane of Bolivia, and the San of Namibia. These societies were chosen because they have minimal exposure to electricity and modern technology, making them ideal subjects to study pre-industrial sleep patterns.
The studyparticipants were equipped with actigraphy watches, which are devices that measure movement and can be used to infer sleep patterns. The data collected was analyzed to determine the duration and timing of sleep, as well as the presence of any seasonal variations in sleep patterns.The resultsof the study showed that all three societies had similar sleep patterns, with sleep periods averaging 6.9-8.5 hours. This suggests that these sleep patterns are likely characteristic of pre-modern era Homo sapiens. The study also found that there were seasonal variations in sleep patterns, with shorter sleep periods during the rainy season and longer sleep periods during the dry season.
One interesting finding of the study was that the pre-industrial societies had a biphasic sleep pattern, meaning that they had two distinct sleep periods per day. This is in contrast to the monophasic sleep pattern of industrial societies, where people typically have one consolidated period of sleep per day. The authors suggest that the biphasic sleep pattern may have been an adaptation to pre-industrial environments, where it may have been more beneficial to have two shorter sleep periods per day in order to better respond to potential dangers or opportunities during the night.
The studyalso found that the pre-industrial societies had a higher percentage of deep sleep, known as slow-wave sleep, and a lower percentage of rapid eye movement (REM) sleep compared to industrial societies. This suggests that pre-industrial societies may have a greater need for deep sleep to support physical activity and recovery.
In summary,the study by Yetish et al (2015) provides valuable insights into the natural sleep patterns of pre-industrial societies and how they differ from those of industrial societies. These findings may have implications for understanding the impact of modern lifestyle and environment on sleep patterns and the potential health consequences of these changes.
However, it's also important to note that the study was conducted on three specific pre-industrial societies and may not be generalizable to all pre-industrial societies or to all people. Further research is needed to fully understand the implications of these findings and how they can be applied to modern society.
In any case,this study gives us an insight into the importance of natural sleep on human health and how modern lifestyle changes affect it. It's a reminder that we should pay attention to our sleep patterns and try to incorporate natural sleep habits in our daily routine to achieve optimal health.
Yetish G, Kaplan H, Gurven M, Wood B, Pontzer H, Manger PR,Wilson C, McGregor R, Siegel JM. Natural sleep and its seasonal variations in three pre-industrial societies. Curr Biol. 2015 Nov 2;25(21):2862-2868. doi: 10.1016/j.cub.2015.09.046. Epub 2015 Oct 17. PMID: 26480842; PMCID: PMC4720388.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720388/