Patients with concussion or post-concussion syndrome sometimes say that looking at a screen aggravates their symptoms. Have you ever wondered why?
An image on a screen is different from an image on paper or in real life. The pixels on a screen change quickly, “refreshing” 40-60 times per second. This photo is a screen shot of a video I took of a laptop screen. Here, the refresh rate of the laptop is slightly different from the recording rate of my phone, so you see a bit of a waver in the image. This isn’t exactly how someone with a concussion would see the screen, but it’s a way to begin understanding what’s going on.
Now normally, our brains ignore the refreshing of the pixels on a screen, and just focus on the image or text they’re presenting. We often don’t even realize the screen image is any different from an image on paper. But there is evidence that after a concussion, the brain has trouble ignoring things that are irrelevant to the task at hand. This is the focus of my research, and a topic near and dear to my heart. When it’s healthy, the brain is really good at not responding to stimuli that don’t matter. If you think about it, that’s a really good thing - we don’t want every small, insignificant stimulus distracting us from the task at hand. After concussion, though, it’s hypothesized that difficulty ignoring irrelevant stimuli cause problems focusing on the things that ARE important and relevant. If the brain is “distracted” by a screen’s refresh rate, it might be harder to take in the information on the screen. Noticing the waver might also lead to headaches or feelings of nausea or dizziness.
Right now, the explanation of why this is aggravating is just a theory, but it’s often helpful for concussion clinicians to think of possible reasons why certain things are symptom triggers. This is how clinical practice drives research - these theories can be tested, and rehab interventions can be perfected. So just give this a thought the next time a patient tells you screen time is a problem.