For many of us, our cellphones are almost constantly in our hands – and now, a study has highlighted the effects on brain activity that can happen when we cut back on using them.
The research involved 25 young adults aged between 18 and 30, who were asked to restrict their smartphone use as much as possible for 72 hours: only essential communications and work-related activities were allowed.
Researchers from Heidelberg University and the University of Cologne in Germany used magnetic resonance imaging (MRI) scans and psychological tests before and after the phone diet to determine what kind of effect this had on neural patterns and activity.
“We used a longitudinal approach to investigate effects of smartphone restriction in smartphone users,” write the researchers in their published paper.
“Associations between changes of brain activation over time and addiction-related neurotransmitter systems were found.”
During the scans run after the 72-hour period, the participants were shown a variety of image prompts – including pictures of smartphones turned on and turned off, as well as more ‘neutral’ images showing subjects such as boats and flowers.
When phone image prompts were used, changes were observed in parts of the brain linked to reward processing and cravings, similar in some ways to brain signals connected to substance addictions, suggesting our phones can be addictive like nicotine or alcohol.
That the changes seen in the brain were associated with dopamine and serotonin systems backs up this idea of phone addiction. ScienceAlert reports that these two neurotransmitters are linked to multiple brain functions, including compulsive behaviour and mood control.
Based on the psychological tests, however, there were no changes in the mood of the participants or any feelings of craving, despite the limited phone access. Some volunteers did report improvements in mood, but this didn’t show up in the test data as significant.
The study, which was published in Computers in Human Behaviour, didn’t delve into any detail about why the smartphone behaviours prompted the brain activity changes, but there are likely to be several factors at play. It’s possible that not all phone-based activities are as addictive as others.
“Our data do not disentangle craving for smartphone use and craving for social interaction, nowadays two tightly intertwined processes,” write the researchers.
“Although our data shows relatively robust findings without unravelling these processes, future studies should clearly aim to address this aspect.”
Scientists are still figuring out how phones are changing our lives, and our brains – it’s less than 20 years ago since the first iPhone appeared – but now we know a little more about some of the subtle withdrawal symptoms that happen when we aren’t picking up our devices every few minutes.
“The identified neural mechanisms may substantially promote addictive behaviour in people at risk for excessive smartphone use,” write the researchers.
Study details
Effects of smartphone restriction on cue-related neural activity
Mike Schmitgen, Gudrun Henemann, Julian Koenig, et al.
Published in Computers in Human Behaviour in June 2025 edition.
Abstract
With the increasing popularity of smartphones in the past decades, physical, social, and psychological consequences of excessive smartphone use (ESU) have been increasingly debated. Cue-reactivity (CR) has been discussed as a core mechanism driving this behaviour, and previous studies have highlighted distinct neural mechanisms underlying CR in individuals with ESU. Here, we used a functional MRI (fMRI) CR-paradigm to investigate the effects of smartphone restriction over 72 h in 25 young adult smartphone users. The CR-task used contrasts of images showing smartphones vs. neutral stimuli and active vs. inactive smartphones. Region-of-interest based correlations with psychometric scores were performed, and activity changes after 72 h were investigated on a neurochemical level using neurotransmitter probability maps. CR-related brain activity changes over time were most prominent in the nucleus accumbens and anterior cingulate cortex (p < 0.001). Such changes were significantly associated with dopamine- and serotonin-receptor probabilities (pFDR < 0.05). Significant associations between parietal cortex activity and craving were detected (p < 0.05). This study provides evidence for CR-related modulation of neural activity in key regions of salience, motor-inhibition, and reward processing after 72 h smartphone restriction. The identified neural mechanisms may substantially promote addictive behaviour in people at risk for ESU.
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