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# Phones moved everyone's bedtime by an hour. Only people with fixed mornings lost sleep.
- URL: https://www.dailyferment.com/how-phones-affect-sleep-toba-qom-study/
- Published: 2026-11-01T01:00:00.000Z
- Updated: 2026-11-01T00:59:59.000Z
- Description: A 12-year study in Argentina found bedtimes moved an hour as electricity and phones arrived. Only the people whose mornings could not move lost sleep.
- Author: Rana Bilal Zafar
- Tags: Science & Health, #reframe

Tonight, at 2 a.m. on Sunday 1 November 2026, most of the United States sets its clocks back an hour, and "when does time go back" is one of the top searches in the country. A study published two weeks ago shows the slow version of that hour. Researchers followed Toba/Qom communities in northern Argentina from 2012 to 2024, while electricity and then smartphones arrived. Bedtimes moved about an hour later in both the rural and the town groups. Only the rural group lost sleep, 35 minutes a night, and their wake-up time barely moved. And phones and electricity, on their own, did not explain the shift.

## What the study measured

The paper, by Leandro Casiraghi, Horacio de la Iglesia and colleagues, came out in Current Biology on 15 October 2026\. It draws on more than 12,000 nights recorded with wrist sensors from 156 people, 93 in rural communities around Vaca Perdida in Formosa province and 62 in the town of Ingeniero Juarez, which had electricity earlier. The rural communities were connected from around 2016\. By the authors' account, no participant owned a smartphone in 2018\. By October 2024 about half did.

**12 years**Toba/Qom sleep recorded from 2012 to 2024 in northern Argentina

**12,000+**nights measured by wrist sensors, from 156 people

**\~1 hour**later sleep onset over 2014 to 2024, in both rural and town groups

**35 min**less sleep a night, rural group only; no loss in town

Source: Casiraghi et al., Current Biology, 15 Oct 2026 (model predictions for 2014 to 2024).

Over the decade from 2014 to 2024 the model puts sleep onset about 53 minutes later in the rural group and 54 minutes later in the town group. That is the bedtime half of the story. The part I find more useful is the morning. Town residents also woke about 52 minutes later, so their nights kept the same length. Rural residents woke only about 19 minutes later, a change too small to be sure of, and their nights shrank by 35 minutes.

![Chart of the change in sleep from 2014 to 2024 in Toba/Qom communities: in town, bedtime 54 minutes later and wake time 52 minutes later with no sleep lost; in rural communities, bedtime 53 minutes later and wake time 19 minutes later, so 35 minutes of sleep lost](https://storage.ghost.io/c/d7/b7/d7b77195-48c5-45ab-8688-51750879d1d6/content/images/2026/10/df88-fixed-morning.png)

Card by Daily Ferment. Source: Casiraghi et al., Current Biology, 15 Oct 2026.

## My first reaction: it's the phones

I expected this to be a phone story. A screen in the hand at 11 p.m. is the easy villain, and the timing fits: electricity first, then a public internet antenna, then phones in half the households.

Guess first: in these communities, how much later did smartphone users fall asleep than people without one?

**13 minutes**, according to an earlier study in the same communities that the authors cite.

The data push back. An earlier study in these same communities found smartphone users fell asleep only 13 minutes later than non-users, far too little to move a whole community by close to an hour. When the authors added electricity access and a "smartphones and internet era" to their model, the drift kept going at about seven minutes a year. They write that "neither the introduction of electricity into rural areas nor the 'smartphone era' can explain by themselves" the change, and they are careful to add that this does not rule either one out. Their reading is broader: a whole way of living that arrives with power and connection, including television prime time that in Argentina runs from 21:00 to midnight and football that can start at 22:00.

So the evening moved for everyone, for more reasons than one gadget. What decided whether that cost anything was the other end of the night. The authors suggest the rural group could not sleep later because of sunlight, heat and the morning's work: firewood, livestock, gathering. The clock did not hold their mornings in place. The day did.

## The same argument, fought over school bells

![A yellow school bus parked by green trees under a cloudy sky](https://storage.ghost.io/c/d7/b7/d7b77195-48c5-45ab-8688-51750879d1d6/content/images/2026/10/df88-split.jpg)

Illustrative. Photo by [Element5 Digital](https://unsplash.com/photos/school-bus-near-green-trees-under-cloudy-sky-during-daytime-7K%5FagbqPqYo?ref=dailyferment.com) on [Unsplash](https://unsplash.com/photos/school-bus-near-green-trees-under-cloudy-sky-during-daytime-7K%5FagbqPqYo?ref=dailyferment.com)

That is the shape of a policy fight I had thought of as being about education. In October 2019 California passed Senate Bill 328, which says a public high school day "shall begin no earlier than 8:30 a.m." and a middle school day no earlier than 8:00, in force from July 2022\. The law does not try to get teenagers to bed earlier. It moves the fixed end of the night, the one end a school board can actually move. The Toba/Qom numbers are a clean natural version of the same bet: when bedtime drifts and the morning cannot, the night is what gives.

One line in the bill stopped me. Section 46148(d): "This section shall not apply to rural school districts." The bill does not say why, and I won't guess at California's reasons. But it is a striking echo. In the Toba/Qom data, the rural group was the one whose morning could not move, and the one that lost the sleep.

The cross: the soft edge and the hard edge of the night

#### Toba/Qom communities, 2014 to 2024

- *Evening:* sleep onset about 53 to 54 minutes later in both groups
- *Morning, town:* wake time about 52 minutes later; no sleep lost
- *Morning, rural:* wake time about 19 minutes later, not significant; 35 minutes of sleep lost
- *What held the rural morning (authors' reading):* sunlight, heat, firewood, livestock

#### California SB 328, 2019

- *Evening:* not addressed; the law does not try to set bedtimes
- *Morning, high schools:* no earlier than 8:30 a.m.
- *Morning, middle schools:* no earlier than 8:00 a.m.
- *In force:* by 1 July 2022; does not apply to rural school districts

Sources: Casiraghi et al., Current Biology, 15 Oct 2026; California SB 328, Chapter 868, Statutes of 2019.

I wrote earlier that [AI hasn't paid off outside tech, and electricity took four decades](https://www.dailyferment.com/ai-productivity-paradox-apollo-slok-dynamo/). This study is a reminder that electricity changes the evening long before it shows up in anyone's productivity figures. And it is a cousin of what I found with [deadlines that move every year](https://www.dailyferment.com/deadline-extensions-teach-people-to-wait/): people adjust to the edge that is soft and pay at the edge that is hard.

## What tonight's extra hour does and doesn't do

Tonight's change is one night of extra sleep for people who can use it. The study's own seasonal numbers show how much the sun matters here: in these communities, each extra hour of daylight came with about 22 minutes less sleep. Changing the clock does not change that. What I take from the paper is narrower and, I think, more practical. If you want to know whether your evenings are costing you sleep, look at your mornings. If yours can move with your bedtime, a late phone costs you timing. If it cannot, it costs you hours.

Established

The study's numbers: about an hour later to sleep in both groups, 35 minutes less sleep in the rural group only, and the finding that electricity and the smartphone era do not explain the drift by themselves. The text of California's SB 328.

Inferred

That a fixed wake time is why the rural group lost sleep. It is the authors' own explanation, offered as likely, not tested.

Still a guess

That the same pattern holds for school and work start times elsewhere. This study is two communities in one province.

The claim, in one sentence

Lights and screens decide when you fall asleep; whoever sets your morning decides whether that costs you sleep.

What I don't know is whether the rural group's mornings will loosen as their lives change further, or whether this is the start of the same long slide the authors think industrial countries went through a century ago.

**More on Daily Ferment:** [Can organ chips replace animal tests? Ask a pilot](https://www.dailyferment.com/can-organ-chips-replace-animal-testing-flight-simulators/) and [The skin cancer AI that won would have sent 18 melanomas home](https://www.dailyferment.com/can-ai-diagnose-skin-cancer-gpt-6-astra-claude-cnn/)

## Sources

- [Casiraghi et al., Longitudinal Study of Toba/Qom Communities Reveals Delay and Shortening of Sleep in Real-Time, Current Biology, 15 Oct 2026 (author manuscript, PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC13674011/?ref=dailyferment.com)
- [Current Biology, publisher record, doi 10.1016/j.cub.2026.09.058](https://doi.org/10.1016/j.cub.2026.09.058?ref=dailyferment.com)
- [Nature research highlight: Sleep declines in rural communities after electricity arrives, 23 Oct 2026](https://www.nature.com/articles/d41586-026-03318-2?ref=dailyferment.com)
- [California SB 328 (2019), chaptered text](https://legiscan.com/CA/text/SB328/2019?ref=dailyferment.com)
- [Fox 29: When daylight saving time ends in 2026, 21 Oct 2026](https://www.fox29.com/news/when-daylight-saving-time-ends-2026-date-clocks-fall-back-one-hour?ref=dailyferment.com)