After nearly 20 years as a stay-at-home mom, I returned to the workforce full-time and found myself working in front of a computer 8 hours a day. It took a while to figure it out, but spending that much uninterrupted time working at a computer created not only muscular tension in my shoulders but an overall tension in my body.

Initially, I added more movement breaks, which did help. Still, at the end of each day, I felt exhausted and uneasy. It was just a pervasive, unpleasant sensation, like my nervous system was being hijacked all day and I had to spend the evening bringing it back down. Reading about ocular lock made me wonder if it had as much to do with staring at the computer as with sitting all day.

I started experimenting with the 20-20-20 rule, which is pretty simple: every 20 minutes, look at something at least 20 feet away for 20 seconds. I don't follow it perfectly, but when I remember to do it, I notice a difference. Looking away from the computer, letting my eyes focus on something across the room or outside the window, and preferably getting up and moving for a minute seems to interrupt that gradual build-up of tension.

Our Eyes Are Designed for Movement

Ocular lock isn't a medical diagnosis, but it's a useful way to describe what happens when our eyes remain focused on something at the same distance for extended periods of time.

Think about how we use our eyes when we're outside. We're constantly looking near and far, tracking movement, noticing things in our peripheral vision and adjusting our focus as we move through space. Our eyes, head and body are working together to take in and process visual information. Now compare that with staring at a computer screen all day.

Research on digital eye strain confirms that sustained near focus, reduced blinking and the effort required to maintain visual alignment can contribute to eye discomfort, headaches and fatigue. The connection to whole-body tension and nervous system regulation is less established, but it makes sense that sustaining near focus while limiting the usual variety of visual experiences might have effects beyond our eyes.

Twenty Seconds Makes a Difference

The 20-20-20 rule is intended to give our eyes regular breaks from sustained near work. Research suggests that breaks can help reduce eye strain, although there isn't strong evidence that this particular timing is necessary. The benefit appears to come from interrupting the pattern. Looking away, shifting focus and moving the body provide a change in sensory input.

This connects with Physical Intelligence (PQ) and the role of movement in brain development and nervous system regulation. Our brains depend on sensory information from throughout the body to understand where we are and what's happening around us. Vision is part of that system, working alongside our vestibular system, which detects head movement and balance, and proprioception, which tells us where our bodies are in space. Together, these systems help us coordinate movement, maintain balance and navigate our surroundings.

When we spend hours sitting still, focused on a small screen, we're missing out on much of the movement and sensory experiences available to us.

Kids and Screens

This is especially important when we consider children, whose brains and nervous systems are still developing. A 2025 review involving more than 335,000 participants found that each additional hour of daily screen time was associated with 21 percent higher odds of myopia, or nearsightedness. While this doesn't establish that screens cause myopia, it raises concerns about prolonged near work and the time children aren't moving their bodies or playing outdoors.

Get Up & Look Up

I'm not suggesting we abandon our computers or take tablets away from kids. Technology is part of our lives, and it offers tremendous benefits. But our bodies and brains developed to function in a three-dimensional world, with movement and changing sensory information throughout the day.

Whether we're talking about white-collar workers or kids in school, prolonged sitting is only part of the concern. Hours of sustained visual focus may be adding another layer of strain.

Let's intentionally bring movement and visual breaks into screen time. Whether it's a catchy 20-20-20 reminder or something else, find ways to break out of the 2-D and back into the 3-D world we live in.

References

Ha, A., Lee, Y. J., Lee, M., Shim, S. R., & Kim, Y. K. (2025). Digital screen time and myopia: A systematic review and dose-response meta-analysis. JAMA Network Open, 8(2), e2460026.

Redondo, B., Jiménez, R., Vera, J., & Rosenfield, M. (2025). The impact of break schedules on digital eye strain symptoms and ocular accommodation during prolonged near work. Experimental Eye Research, 258, 110463.

Talens-Estarelles, C., et al. (2023). The effects of breaks on digital eye strain, dry eye and binocular vision: Testing the 20-20-20 rule. Contact Lens & Anterior Eye, 46(2), 101744.

Daly-Smith, A., et al. (2018). Systematic review of acute physically active learning and classroom movement breaks on children's physical activity, cognition, academic performance and classroom behaviour. BMJ Open Sport & Exercise Medicine, 4, e000341.