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Smartphones are wrecking teens' sleep, study indicates (opens in a new tab)

medicalxpress.com · 2026-10-21

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Smartphones are wrecking teens' sleep, study indicates

medicalxpress.com · 2026-10-21

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Every claim we could check holds up. Four of five claims match the study. This overall rating is based only on the claims we could check. One claim the study doesn't address.

4 supported
1 not covered

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The source study

Evening Phone Use and Sleep Outcomes Among Youth

JAMA Pediatrics · 2026

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5 claims in this story

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Claim 1 of 5Not coveredThe article says this is one of the first studies to indicate a possible cutoff time for teens' phone use, with use after 10 p.m. and right before bedtime linked to worse sleep outcomes.View evidenceHide evidence

As statedafter 10 p.m.; 5 to 15 minutes before falling asleep

Why this verdict

The association of use after 10 pm and immediately before sleep onset with worse sleep outcomes is supported by the abstract-level profile. However, the novelty claim that this is 'one of the first studies' to indicate a possible cutoff time is not directly verifiable from the abstract-level profile.

Study evidence

Within-person: each additional minute of smartphone use after 10 pm above a participant’s own average was associated with later sleep onset, later sleep offset, and shorter total sleep time.Sleep onset +0.87 minutes per additional minute of use (95% CI, 0.84 to 0.90); Sleep offset +0.37 minutes (95% CI, 0.33 to 0.41); TST −0.43 minutes (95% CI, −0.47 to −0.39); all P < .001.

Study evidence

Use in the final 5 minutes before sleep onset was associated with greater sustained WASO.+0.74 minutes (95% CI, 0.50 to 0.98) additional wakefulness; P < .001

Claim 2 of 5SupportedTeens who use their phones late into the evening suffer from delays in falling asleep, shorter total sleep time and sleep that's more restless and broken, researchers report in JAMA Pediatrics.View evidenceHide evidence

Why this verdict

The abstract-level profile supports associations between greater late-evening smartphone use and later sleep onset, shorter total sleep time, and between proximal pre-sleep use and increased wake after sleep onset. The headline wording is unhedged and somewhat colloquial, but as framed here as an associational claim rather than proof of causation, it is consistent with the paper evidence.

Study evidence

Study evidence

Use in the final 5 minutes before sleep onset was associated with greater sustained WASO.+0.74 minutes (95% CI, 0.50 to 0.98) additional wakefulness; P < .001

Claim 3 of 5SupportedThe researchers analyzed data on 425 kids with an average age of nearly 15 who were participating in an ongoing study of adolescent brain development, and they gathered nearly 7,600 nights of data.View evidenceHide evidence

As stated425 participants; nearly 7,600 nights of data

Why this verdict

The profile reports 425 ABCD adolescents with mean age 14.8 years contributing 7591 person-nights, matching 'average age of nearly 15' and 'nearly 7,600 nights of data.'

Study evidence

Study evidence

Use in the final 5 minutes before sleep onset was associated with greater sustained WASO.+0.74 minutes (95% CI, 0.50 to 0.98) additional wakefulness; P < .001

Claim 4 of 5SupportedOn nights when teens used their phone longer than their personal average after 10 p.m., they slept an average of 20 minutes less and fell asleep 64 minutes later.View evidenceHide evidence

As stated20 minutes less sleep; 64 minutes later sleep onset

Why this verdict

The paper profile reports the same descriptive within-person contrast: on nights with more-than-usual smartphone use after 10 pm, adolescents slept 20.05 minutes less and fell asleep 64.73 minutes later on average.

Study evidence

Claim 5 of 5SupportedTeens glued to their phones were more likely to wake up again within a half-hour after they nodded off, and there was a dose effect in which every extra minute of smartphone use past 10 p.m. above a teen's own average added to later sleep onset and reduced total sleep time.View evidenceHide evidence

As statedevery extra minute past 10 p.m.

Why this verdict

The dose-response portion is supported by adjusted within-person estimates per additional minute of smartphone use after 10 pm: later sleep onset and reduced total sleep time. The wake-after-sleep-onset portion is supported by the proximal-use analysis showing increased WASO concentrated in the first 30 minutes after sleep onset, though the story uses looser wording such as 'glued to their phones' and 'more likely to wake up' rather than the paper's measured WASO minutes.

Study evidence

Study evidence

Use in the final 5 minutes before sleep onset was associated with greater sustained WASO.+0.74 minutes (95% CI, 0.50 to 0.98) additional wakefulness; P < .001

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Context layer

What the story left out

Important study details the story did not include.

Smartphone exposure and sleep outcomes were objectively/passively measured using EARS app smartphone sensing and Fitbit-derived sleep measures.
The story summary mentions repeated-night data but does not reflect the material measurement detail that phone use was passively sensed and sleep was Fitbit-derived.
From intensive longitudinal cohort (person-night panel); Intensive longitudinal cohort (person-night panel); within-between m
Generalizability may be limited because the analytic sample was restricted to Android users with concurrent EARS app data and Fitbit-measured sleep.
The story caveats provided do not mention the Android-user restriction or the requirement for concurrent app and wearable data, which are material limitations in the paper profile.
From intensive longitudinal cohort (person-night panel); Intensive longitudinal cohort (person-night panel); within-between m

6 things the story did carry across

The study was an observational intensive longitudinal cohort analysis using person-night data from adolescents in the ABCD Study, not an experiment.
The analytic sample comprised 425 adolescents, mean age 14.8 years, contributing 7591 person-nights.
Main within-person finding: greater smartphone use after 10 pm than a teen's own average was associated with later sleep onset, later sleep offset, and shorter total sleep time.
Adjusted per-minute estimates after 10 pm showed later sleep onset and shorter total sleep time for each additional minute of use above a participant's average.
Proximal smartphone use immediately before sleep onset was associated with greater sustained wake after sleep onset, with the largest association for the final 5 minutes and wakefulness concentrated in the first 30 minutes after sleep onset.
Causal inference is limited because the evidence comes from an observational cohort analysis.

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study summary

Lead result

secondary data

1Lead resultsecondary dataQuantify within-person and between-person associations between passively sensed cumulative evening smartphone use (hourly cutoffs from 8 pm to midnight) and objectively measured sleep timing and duration outcomes in adolescents.intensive longitudinal cohort (person-night panel)Expand

In plain English

In an intensive longitudinal cohort of 425 ABCD adolescents (7591 person-nights), greater cumulative late-evening smartphone use (hourly cutoffs 8 pm–midnight) was associated within-person with later sleep onset and offset and shorter total sleep time, and smartphone use immediately before sleep onset was associated with increased wake after sleep onset (WASO).

Key findings

Within-person: each additional minute of smartphone use after 10 pm above a participant’s own average was associated with later sleep onset, later sleep offset, and shorter total sleep time.Sleep onset +0.87 minutes per additional minute of use (95% CI, 0.84 to 0.90); Sleep offset +0.37 minutes (95% CI, 0.33 to 0.41); TST −0.43 minutes (95% CI, −0.47 to −0.39); all P < .001.
Descriptive within-person night-level contrasts: on nights with more-than-usual phone use after 10 pm, adolescents slept less and fell asleep substantially later.Mean difference on such nights: TST −20.05 minutes (SD 49.42); Sleep onset delayed by 64.73 minutes (SD 50.95).

What this piece can’t prove

Observational cohort analysis; causal inference is limited by study design (as described in abstract).
Analytic sample limited to Android users with concurrent EARS app data and Fitbit-derived sleep, which may limit generalizability to non-Android users or those without wearable sleep data (sample restriction described in abstract).

2secondary dataAssess whether smartphone use proximal to sleep onset (within 5 to 30 minutes before sleep onset) is associated with objectively measured wake after sleep onset (WASO), including timing of wakefulness concentrated shortly after sleep onset.Intensive longitudinal cohort (person-night panel); within-between multilevel modelsExpand

In plain English

In an intensive longitudinal cohort of adolescents, passively sensed smartphone use in the proximal window before sleep onset (5–30 minutes pre-onset) was associated with greater sustained wake after sleep onset (WASO); the largest association occurred for use in the final 5 minutes before sleep onset (+0.74 minutes of wakefulness), and the increased wakefulness was concentrated in the first 30 minutes after sleep onset.

Key findings

Use in the final 5 minutes before sleep onset was associated with greater sustained WASO.+0.74 minutes (95% CI, 0.50 to 0.98) additional wakefulness; P < .001
Proximal use considered over the final 20 minutes before sleep onset showed negligible association with WASO.negligible

What this piece can’t prove

Observational cohort analysis (cannot establish causality).
Sample limited to Android-using adolescents with ≥14 days of concurrent EARS app and Fitbit data, which may limit generalizability to non-Android users or other age groups.

1 further detail could not be confirmed from the summary.

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