What Excessive Screen Time Does to the Adult Brain

By Mary Grace Descourouez, MS, NBC-HWC

Binge-watching television, watching YouTube videos for hours, or scrolling on your phone every morning may seem harmless, but research shows that too much screen time may be detrimental to your health.

We know children’s brains are affected by spending too much time glued to their cell phones, however research shows that adult brains are also negatively impacted by excessive screen time, defined as more than two hours a day outside of work hours.

Too much screen time can impact our health in a myriad of ways, from eye strain and neck pain to social isolation and mental health, and in some cases, it may cause harm to our brains.

“The negative effects of screen time are insidious because you can’t see what’s happening in your brain as you’re staring at the screen,” says Maris Loeffler, MA, Family and Marriage Therapist, member of the Stanford Lifestyle Medicine Cognitive Enhancement pillar. “If you scrolled on your phone in bed for an hour just one morning, the negative impacts would be minimal. But if it becomes a habit, day after day, month after month, this behavior can take a toll.”

Since the eyes are directly connected to the brain, Loeffler encourages us to think about our eye health to ensure overall brain health. Rather than looking at our phones upon waking, Loeffler recommends starting each morning looking at the horizon or an object outside and far away.

To prevent eye strain throughout the workday, The American Academy of Ophthalmology recommends the 20-20-20 rule for adults who work on a computer. This rule suggests that individuals look at something 20 feet away for 20 seconds every 20 minutes of the day.

What is Happening in the Brain During Screen Time?

This study found that increased use of screens among adults may harm learning, memory, and mental health, as well as the potential to increase the risk of early neurodegeneration. The study shows that in adults aged 18 – 25, excessive screen time causes thinning of the cerebral cortex, the brain’s outermost layer responsible for processing memory and cognitive functions, such as decision-making and problem-solving.

Another study found that adults who watched television for five hours or more per day had an increased risk of developing brain-related disease like dementia, stroke, or Parkinson’s.

This study found that excessive screen time can hinder sleep, especially when looking at screens late at night. Light from the screen can delay melatonin release from the brain’s pineal gland, impacting the body’s natural circadian rhythm and causing difficulty sleeping.

Additional studies found that adults who engage in excessive screen time or have a diagnosed smartphone addiction had lower gray matter volume. Gray matter is brain tissue essential for daily human functioning and is responsible for everything from movement to memory to emotions. Gray matter volume naturally decreases as we age, so along with reducing screen time, engaging in activities that maintain our gray matter volume and promote brain health, such as exercise and movement, restorative sleep, social engagement, and stress management, is crucial.

“Passive screen time is like eating sugar but for your brain. It ‘tastes’ good, and you want it now, but you’re not actually feeding yourself. You’re not giving your brain any nutrition,” says Loeffler. “Instead, replace screen time with an intentional healthy habit that feeds your brain in a healthy way. Lifestyle medicine activities, like exercise, good sleep, social connection, and stress management, function like ‘nutrition’ for your brain and mental health.”

Specifically, Loeffler cautions us not to pick up the phone after the alarm goes off in the morning. She explains that looking at our email or social media on our phones while still in bed jolts the nervous system and can trigger the fight-or-flight response since we aren’t fully awake yet.

Also, if we look at our phones first thing every morning, we create a pattern and can set the flight-or-flight response as our default mode of operation. So, not only does this behavior set an anxiety-filled tone for the day, but we are also training our brains to be more hypervigilant in general.

“One of the biggest issues with picking up the phone right away in the morning is that when you have an object close to your face, it’s registered as a threat,” says Loeffler. “You wouldn’t want to wake up and look a bear in the face every morning. On a physiological level, it’s the same thing.”

Practice of the Month: No Screen Time for the First Hour of the Day

Stanford Lifestyle Medicine experts recommend no screen time for the first hour of the day to support cognitive enhancement. Instead, we suggest engaging in a lifestyle medicine activity upon waking to promote whole-body health:

  • Exercise
  • Call a friend or family member
  • Prepare a healthy breakfast
  • Meditate and count your blessings
  • Listen to music
  • Create a gratitude list
  • Read a book
  • Spend time outside and get morning light

“How do you want your day’s energy and mood to start?” says Loeffler. “Intentionally implementing a morning routine that reflects lifestyle medicine choices instead of screen time sets a positive tone for the day and supports brain health and cognitive enhancement.”