Welcome to Running: A FEVER, a show about fitness, diet, and medicine. I’m Michael Davis, and my goal is to live a long, healthy, happy, active life right up to the very end.

We’re in the middle of a series about Screentime and Your Health. And by the way, you can access the entire series on a YouTube playlist called Screentime and Health. You can find it on my channel at YouTube.com/@runningafever. We’ve already enlightened ourselves on two aspects of this topic: sedentary life and sleep effects. Today, we’re moving on to how screen time affects our brains.

Ever opened your phone to check one thing… and suddenly it’s 45 minutes later and you can’t remember what you were doing in the first place? Or maybe you’ve felt scattered, foggy, or just mentally off after a long day of screen time? This episode is all about digital fog — the subtle but powerful ways that screens are reshaping our brains. We’ll explore how excessive screen use affects memory, focus, and decision-making. We’ll talk about the neuroscience behind screen addiction, the shrinking of gray matter, and why multitasking might be making us less productive — not more. But I’m not here to scare you. I want to understand what’s happening, and more importantly, what we can do about it.

I’m always fascinated by the science of health, so I’ll start with that. The thinning of the cerebral cortex and a reduction in gray matter. Sounds ominous. Yes, excessive screen time can PHYSICALLY change your brain.

According to an article in Psychology Today, Neuroimaging studies have shown that people who spend large amounts of time on screens–especially those with internet or gaming addictions–often exhibit gray matter atrophy, which means a shrinking or loss of brain tissue, particularly in areas responsible for decision-making, emotional regulation, and impulse control.

One of the most affected regions is the frontal lobe — the part of the brain that helps us plan, prioritize, and stay focused. It’s also where we regulate our emotions and make socially appropriate decisions. When this area is compromised, it can lead to impulsivity, poor judgment, and difficulty concentrating.

There is actually a named disease associated with this. A National Institutes of Health paper states that “[Dr. John Martyn Harlow, a physician, first described this collection of symptoms as ‘frontal lobe syndrome’ after his research on the famous Phineas Gage, who suffered a dramatic change in behavior as a result of trauma. Thus, an abnormality in the frontal lobe could dramatically change not only processing but personality and goal-oriented directed behavior.” As an aside, the NIH has a warning on its website that information might not be up-to-date due to the government shutdown in the United States, as I am researching this episode. Just an example of how government funding affects things.

Another area impacted is the insula, which helps us process emotions and develop empathy. Damage here can affect how we connect with others–which might explain why excessive screen use is linked to social withdrawal and reduced emotional sensitivity.

And then there’s the cerebral cortex — the brain’s outermost layer, responsible for higher-order thinking, memory, and learning. Studies have found that excessive screen time, particularly in adolescents, is associated with reduced cortical thickness, which in turn correlates with poorer cognitive performance. See my link to the Psychology Today article in the references section of my blog post at http://RunningAFEVER.com/434.

Now this isn’t just about kids. Adults are affected too. The more time we spend on screens–especially in passive or addictive ways–the more we risk dulling the very parts of our brain that help us thrive in the real world. But here’s the good news: the brain is adaptable. Neuroplasticity means we can rewire and rebuild — but it starts with awareness, which is what we’re cultivating right here, right now.

This digital fog includes a sense of mental static–impaired focus, impaired memory, and impaired decision-making. Do you really want these things to be impaired? Is it worth it to get immediate stimulation from electronic sources?

Let’s talk about this. The fuzziness, the forgetfulness, the constant distraction. If you’ve ever felt like your brain is running on low battery after a day of scrolling, streaming, or multitasking, you’re not alone. Research indicates that excessive screen time can impair cognitive functions, including attention, memory, and decision-making.

The idea that multitasking is a useful skill is a myth. I’ve been aware of this for a while. My view is supported in a book called “Great at Work” by Morten Hansen, in which he describes how he found that successful people don’t try to multitask, but instead focus intently on one task or project. Screens train our brains to switch tasks rapidly — from emails to texts to social media to news. But this constant switching comes at a cost. The prefrontal cortex, which helps us focus and make decisions, becomes overstimulated. Instead of deep concentration, we receive surface-level attention — and that leads to mental fatigue and reduced productivity.

Michael Rich is a pediatrician, associate professor of pediatrics at Harvard Medical School, director of the Center on Media and Child Health at Boston Children’s Hospital, and associate professor of social and behavioral sciences at the Harvard T.H. Chan School of Public Health. He says, “It’s not how long we’re using screens that really matters; it’s how we’re using them and what’s happening in our brains in response…We must be flexible enough to adapt to evolving technology, but choose how to utilize it effectively. Fire was a great discovery to cook our food, but we had to learn that it could hurt and kill as well.” By the way, Dr. Rich is also known as “The Mediatrician.”

What about memory? Memory isn’t just about storing information–it’s about encoding it properly. When we’re distracted by notifications or bouncing between apps, our brains struggle to consolidate what we’ve learned. Even if we’re physically present in a meeting or a class, we may not retain the information because our attention is fragmented. For example, teens who stay up late texting or gaming often miss out on REM sleep — the phase critical for memory consolidation. So even if they’re awake in class the next day, they may not remember what they learned the day before.

Decision-making is also influenced by screen time and contributes to the digital fog we’re discussing here. Many digital platforms — especially social media and games — use variable reward systems, similar to those found in slot machines. This activates the brain’s self-regulation systems, making it harder to resist distractions or make thoughtful decisions.

Screens aren’t inherently bad — but how we use them matters. To protect our focus, memory, and decision-making, we need to create space for deep work, rest, and reflection.

Let’s look at another aspect of the mental effects of screens in our lives, addiction, and the emotional toll of screen addiction. We’ve alluded to addiction in this series as being especially impactful on the brain in a negative way. Addiction doesn’t just apply to substances like drugs and alcohol; it can also apply to screens. But screen addiction isn’t just about spending a lot of time online. It’s about compulsive use–the kind that interferes with daily life, relationships, sleep, and emotional well-being. And it’s more common than we think.

At the heart of screen addiction, from a biological perspective, is dopamine–the brain’s reward chemical. Every notification, like, or scroll triggers a tiny hit of dopamine, reinforcing the behavior. Over time, our brains begin to crave that stimulation, and we find ourselves reaching for our phones without even thinking. By the way, if you want to know a lot more about brain chemicals, check out my 7-part series starting with episode 139. You can also find them all in a YouTube playlist called “4 Brain Chemicals” on my channel, which is at http://YouTube.com/@runningafever.

This constant stimulation can lead to anxiety when we’re disconnected, or instability when interrupted, or restlessness when we’re not engaged with a screen. And emotionally, it can be draining. We may feel more isolated, even though we’re constantly “connected.” We may compare ourselves to curated lives online, leading to low self-esteem, FOMO, or even depression.

A blogger known only as “Joe” relates that “Not only is my phone the source of distraction for my brain, it’s also the source of almost every negative emotion I feel in a day. From anger, frustration, and impatience around the kids, to intolerance, stress, insecurities, and anxiety. They all usually stem from looking at my phone.”

Screen addiction also affects our relationships. We might be physically present but emotionally absent. Conversations get interrupted by notifications. Eye contact fades. Over time, this can erode intimacy and trust.

But here’s the hopeful part: awareness is the first step. Once we recognize the patterns, we can start to change them. We can retrain our brains, reclaim our attention, and reconnect with ourselves and others.

So what have we learned today? Screens are powerful tools — but they’re also powerful influences. They shape how we think, how we feel, and how we connect. And when we use them without intention, they can leave us mentally foggy, emotionally drained, and disconnected from the present moment.

But here’s the good news: our brains are resilient. Neuroplasticity means we can change–we can rebuild focus, restore memory, and reclaim our attention. It starts with awareness, and it grows with action.

Perhaps today, you can take a break. You turn off notifications. You go for a walk without your phone. You give your brain the space it needs to breathe.

Our series continues with Part 4: “Digital Distress in Families.” How screen time affects families—from tantrums and anxiety in kids to emotional distance in adults. It’s a conversation you won’t want to miss, and I hope you’ll join me. And remember, if you’ve got the fever, keep it burning, and if you don’t, catch the fever, and I will see you next time on Running: A FEVER.

References:
https://www.psychologytoday.com/us/blog/mental-wealth/201402/gray-matters-too-much-screen-time-damages-the-brain
https://www.ncbi.nlm.nih.gov/books/NBK532981/
https://hms.harvard.edu/news/screen-time-brain
https://tinyurl.com/raf-great-at-work2
https://www.thebodycoach.com/blog/im-addicted-to-my-phone/