Abstract
Electric light has profoundly altered human sleep by enabling extended activity after dark. To investigate its effects, we studied native Toba/Qom communities in northern Argentina from 2012 to 2024, comparing rural groups newly introduced to electricity with semi-urban groups with a continuous access to it. Fitting linear models over 12,000+ sleep events from 156 participants across this period, we examined changes in sleep dynamics over time. While both groups presented larger delays in sleep timing and reductions in sleep regularity, rural communities lost a full hour of sleep in only ten years. Changes in urban areas suggest additional influences from modern technologies beyond electric light, such as smartphones and the internet. Such huge changes in such a short period of time highlight the powerful role of electricity and technologies in shaping human sleep and underscore the importance of carefully managing technological transitions in underserved communities.