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How far away is your phone right now? When did you last look at it? For many of us, these digital devices are almost constantly in our hands, and a new study highlights 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.
Images of phones and other objects were used to spark brain activity. (Schmitgen et al., Computers in Human Behavior, 2025)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. These two neurotransmitters are linked to multiple brain functions, including compulsive behavior 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 didn't delve into any detail about why the smartphone behaviors 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 does 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 unraveling 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 mobiles every few minutes.
"The identified neural mechanisms may substantially promote addictive behavior in people at risk for excessive smartphone use," write the researchers.
The research has been published in Computers in Human Behavior.
