Sleep Shortened and Shifted Later as Electricity Reached Argentine Communities, Study Finds

The evidence is an observational, longitudinal study in people, posted as a bioRxiv preprint in 2025. It has not been peer reviewed. It followed 156 participants and analysed more than 12,000 sleep events recorded with actigraphy, a method that estimates sleep from body movement.

The work ran from 2012 to 2024. Some rural groups were newly introduced to electricity after 2016. Other, semi-urban groups had had electricity for longer. Because the same communities were followed over time, the team could see sleep change as it happened. Many earlier studies compare different groups at a single moment.

According to the authors, both groups showed delays of up to 1.4 hours in sleep timing. Participants from rural communities lost a full hour of sleep within just a decade. The authors analysed the data with linear mixed-effects models, a statistical approach for repeated measurements on the same people.

The period covered the arrival of electricity in rural areas and, later, the spread of the internet and smartphones. It is tempting to blame evening light and screens. The authors say their models do not support that simple story. They report that these events alone cannot fully explain the shifts in sleep timing.

Instead, they suggest that broader processes of modernization and acculturation, beyond electric light and digital devices alone, may be driving the changes. That is an interpretation, not a tested result.

The authors say direct, long-term evidence that artificial light and digital technology delay and shorten sleep has been scarce. They write that the changes seen here mirror, within a single decade, the likely path of human sleep across the 20th and early 21st centuries. For people elsewhere, the finding is a reminder that later, shorter sleep is linked to many features of modern environments, not only to a bright screen at night.

Press coverage went in a slightly different direction. Nature's news report said residents slept an average of 35 minutes less per night after gaining electricity, which it linked to access to the internet and smartphones. Nature cites a peer-reviewed version of the study in Current Biology. We have not seen that version, and its numbers may differ from the preprint.

Other limits follow from what is available. The results come from one set of communities and may not apply to other populations.

What to watch next

What to watch next is whether the peer-reviewed Current Biology paper confirms the preprint's figures, and whether later work can separate the effects of light, devices and wider social change on sleep.

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