Episode 2 · Launch seriesWithin-person observational studyVideo coming soon⏱ 3:12 video · 📖 1 min read

Teens on Phones After 10pm Fall Asleep an Hour Later

Zhao, Hale & Christakis, JAMA Pediatrics, 2026 · Topics: Sleep · Phones & Screens

⚠ General information only — this page explains one study and isn't medical or parenting advice for your specific child.

Subscribe on YouTube ↗Read the paper (DOI) ↗

What's the short answer?

On nights when teens used their phones more than usual after 10pm, they fell asleep about 64.7 minutes later and slept about 20.1 minutes less — and a 20-minute phone-free buffer before bed made most of the effect fade.

What did the study do?

The researchers tracked 425 US adolescents across 7,591 nights. The phone itself logged use and a Fitbit logged sleep — and each teen was compared only to themselves, night by night.

What did it find?

On nights with heavier-than-usual phone use after 10 p.m., sleep onset came about 64.7 minutes later and total sleep was about 20.1 minutes shorter.
Every extra minute of post-10 p.m. use above a teen's own average meant sleep onset 0.87 minutes later and total sleep 0.43 minutes shorter.
Phone use in the final 5 minutes before sleep was linked to more wakefulness after sleep onset; use that ended 20 minutes before sleep showed a negligible effect.

What it didn't prove

This is an observational within-person study: heavy late use and later, shorter sleep moved together night by night. It is phrased as linked, not proof — and it studied use after 10 p.m. specifically.

🌙 One thing to try tonight

Set a 20-minute phone-free buffer before bed — phones down, ideally charging outside the bedroom, for the last 20 minutes of the night.

Frequently asked questions

Why 20 minutes?

In the data, phone use that ended about 20 minutes before sleep showed a negligible effect, while use in the final 5 minutes was linked to more wakefulness. The buffer comes straight from that contrast.

Was this self-reported?

No — phone use was logged by the phone and sleep by a Fitbit, across 7,591 nights, which is stronger than recall questionnaires.

📄 The paper at a glance

Zhao Y, Hale L, Christakis DA. Evening Phone Use and Sleep Outcomes Among Youth. JAMA Pediatrics. 2026.

DOI: https://doi.org/10.1001/jamapediatrics.2026.4902 ↗ · Video: 3:12 · Coming soon to youtube.com/@ParentingByScience

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The takeaway

You don't need a total night-time ban to use this finding — a 20-minute buffer before bed is where most of the effect faded.

This site explains studies for general information — it isn't medical or parenting advice for your specific child.

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Topic: Sleep Topic: Phones & Screens All within-person observational study studies Research for tweens & teens Paper index

Episode 12⏱ 3:24 video · 📖 1 min read

Meta-analysis Video coming soon

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Try tonight: Convert some solo screen time into together time: co-watch, co-play, and talk about what is on the screen while it is on.

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