Reducing screen time can have positive knock-on effects on sleep and well-being – but how does it affect stress and HRV?
It’s a nuanced question, because heart rate variability (HRV) has been shown to drop during periods of adjustment away from screens, which is usually taken as a sign of rising stress.
But researchers liken that to the impact of withdrawal – and participants have reported improved mental health in the same period.
In this guide, we explain what happens to stress and HRV during and after heavy phone use.
Read next: 5 ways to reduce screen time
Key takeaways
- 20 minutes of social media raised neither heart rate nor cortisol in a trial of 59 people.
- Students who cut their phones to under two hours a day saw their HRV fall – while their wellbeing, mood, sleep and stress scores all improved.
- The students whose HRV fell furthest reported the strongest cravings.
The HRV effect of a phone detox
Heart rate variability is the variation in the gaps between your heartbeats. A higher variability timing usually means your nervous system is in a more rested state. Read our ultimate guide to HRV to learn more.
Researchers in Idaho gave 59 people, aged 13 to 55, two twenty-minute phone sessions: one on social media, one watching a playlist someone else had chosen. Everyone did both, in an order drawn at random. They wore heart rate monitors throughout and gave saliva samples before and after, tested later for cortisol, the hormone you release under stress.
Heart rate and cortisol both drifted down as the session went on, whichever thing people were doing. It made no difference how old they were, whether they were men or women, how much social media they used at home, or how they scored on the psychological questionnaires.
Why HRV falls and mental health improves
In Austria, researchers at Krems randomised 111 university students either to reduce their phone use to under two hours a day for three weeks, or to carry on as normal. Forty-five of them also wore a wrist tracker right through: before the trial, during the cutback, and for the weeks afterwards.
Their HRV also fell during the cutback.
However, participants who cut back reported better mental health than the students who had carried on as normal.
That finding came from four standard questionnaires, filled in before the three weeks began, straight after they ended, and again six weeks later. Students rated their own wellbeing, their depressive symptoms, how well they were sleeping, and how stressed they felt. All four improved in the group that cut back, by small to medium amounts, and the widest gaps against the control group were in depressive symptoms and sleep quality.
The students had been averaging about four and a half hours of screen time a day before they started.
The researchers put this down to something like withdrawal from a behavioural habit.
The students whose HRV fell furthest reported the strongest cravings for their phones, and the worst sleep.
Once the three weeks ended, their screen time climbed again, and by the six-week follow-up it was close to where it began. There needs to be more research into the long-term effects of HRV and phone detox, to see if signals rebound later.
For what has actually worked in trials, read our guide to reducing screen time .
Frequently asked questions
Does scrolling raise your heart rate? Not in the Idaho trial. Over twenty-minute sessions, heart rate and cortisol both fell, whether people were on social media or watching a video playlist.
Why did my HRV go down when I cut my screen time? The Austrian students saw the same thing, and the ones whose readings fell furthest reported the strongest cravings and the worst sleep. Their mental health improved over those same weeks. Researchers think it resembles withdrawal. Give it a month.
What does “improved mental health” actually mean here? Four questionnaires the students filled in themselves, covering wellbeing, depressive symptoms, sleep quality and perceived stress. All four moved in the right direction after three weeks of cutting back, by small to medium amounts.
Does the Ultrahuman Ring measure screen time? No. The Screen Time PowerPlug reads the figures your phone already keeps and sets them against your own sleep window, so your wind-down and restriction hours come from when you actually sleep. The ring measures your sleep and your HRV.
References
- Oppenheimer S, Bond L, Smith C. Social media does not elicit a physiological stress response as measured by heart rate and salivary cortisol over 20-minute sessions of cell phone use. PLoS One. 2024;19(4):e0298553. PMID 38568926
- Dale R, Haider K, Majdandžić J, et al. The influence of smartphone reduction on heart rate variability: a secondary analysis from a randomised controlled trial. Health Psychol Behav Med. 2025;13(1):2546376. PMID 40831581
- Pieh C, Humer E, Hoenigl A, et al. Smartphone screen time reduction improves mental health: a randomized controlled trial. BMC Med. 2025;23(1):107. PMID 39985031
- Chin SC, Chang YH, Huang CC, et al. Altered heart rate variability during mobile game playing and watching self-mobile gaming in individuals with problematic mobile game use. Psychol Res Behav Manag. 2024;17:2545-2555. PMID 38973973
- Schmidt-Persson J, Gejl AK, Philipsen KB, et al. Effects of reducing screen media use on mental health, sleep, physical activity, heart rate variability, and behavioral patterns in peergroups of young people: a study protocol for a cluster-randomized controlled trial. BMC Psychol. 2026;14(1):1098. PMID 42204593
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