Societies without electricity sleep for a similar time to modern societies

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By Dr. Annemarie Luik

Bitesize research – a brief article summary from the Sleepio team:

Yetish et al. (2015).Natural sleep and its seasonal variations in three pre-industrial societies. Current Biology, published online 17 October

Do people in pre-modern societies sleep longer? The authors assessed sleep in three pre-industrial societies in Tanzania, Namibia and Bolivia. In these societies, there was no electricity, or associated lighting, entertainment, cooling or heating systems. In total, 1165 nights were recorded with actigraphy across different seasons. The average total sleep period (onset to offset) was 6.9 to 8.5 hours, and total sleep time was 5.7 to 7.1 hours, which is no longer than the average sleep time in modern societies. On average bedtime was 3.3 hours after sunset and awakening was typically before sunrise. Sleep consistently coincided with time when light and temperature were at their lowest. Napping occurred on <7% of days in winter and <22% of days in summer. Insomnia was rare. The authors suggest that the natural daily temperature cycle, often eliminated in modern societies, is a potent regulator of sleep in pre-industrial societies.

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