The ability to concentrate is still one of the most challenging things for me. This becomes especially apparent when reading or writing of a screen or monitor. You can imagine that this is hard to work around in daily life. So anything that can help alleviate this challenge is very welcome.
After looking into different (mostly technical) details of modern monitors. I found a couple of things that could be helpful regarding the amount of strain I (and we all) put on our brain and eyes during use. Crazy fact, our eyes are actually part of our brain outside of the skull
But anyhow…
Without making things overly complicated these are some points that stand out for me in a sea of technical specifications and confounding factors. Like the brain a modern day monitor is pretty complicated, so bear with me. Or you can just scroll down for the takeaways 
One the one most important things is called “flicker”. Flicker in layman terms is a light source that isn’t completely stable or constant. Sort of like a flashlight repeatedly switching on and off. It blinks, or for lack of a better word it flickers 
You can imagine looking into such a light for longer periods of time wouldn’t be really all that pleasant. But this is actually what we’re doing when using a monitor, albeit in a way less obvious and subtle manner. It is just an inherent drawback of how a modern monitor works. A lot of things can influence the amount of flicker your monitor or screen has and here are but a few.
The first one is the refresh rate. The refresh rate is the number of times per second that your monitor displays a new image. This is written in Hertz but often abbreviated as Hz. Most monitors have a refresh rate of 60Hz. So 60 times per second a new image called a frame, will be displayed.
Among other things, the switching between the old and new frames can create flicker. It happens so fast that your brain stitches it all together so it still looks as one continuous image. You probably won’t notice this but it’s putting extra stress on our brain to process this subtle flashing light source. In recent years more expensive monitors have been released with higher refresh rates like 120 or even 240Hz, and so creating less flicker.
Most hardware today is actually capable of flicker free operation, but because manufacturers use certain technology to extend the life and energy efficiency of a monitor, this is still an issue.
The higher refresh rate also gives the advantage of increased fluidity when motion occurs. Whenever I’m looking at a screen I get instantly nauseous when there is a stutter during a camera pan, a roller coaster feeling if you will. With an increased refresh rate you get more frames or steps to a movement and it feels way easier for my brain to comprehend and process what I’m seeing.
Below a video to illustrate the effect of increased fluidity when the number of frames increases. You probably can’t see the difference between 60 and 120 frames as your screen could very well be the limiting factor, if it’s running at 60Hz.
Another flicker related thing is the brightness. I used to lower the brightness all the way down, not knowing this could be introducing extra flicker due to the hardware design of the monitor. There are two main methods to lower the brightness of a screen. Long story short; the Direct Current (DC) dimming method is the preferred one.
The other method Pulse Width Modulation (PWM) method works by quickly switching off for a period of time when a new image is displayed. So at 30% brightness, the screen is turned off 70% of the time. This happens at the refresh rate (typically 60Hz), so very fast. Again you won’t notice this, your brain and eyes just see a seemingly still image. But in the background all of this is happening constantly. Of course this is something that should be avoided as this will increase the discernible strobe-like light effect.
The DC method however has the advantage that it dims the screen by giving the LEDs/crystals in the display less electrical current in which the screen will simply light up less brightly. That way it doesn’t introduce any extra flicker. So that’s why the DC method is favored in my particular case. However…
If you already have a monitor which uses the PWM method you can also dim your screen via a handy app, called Iris (see footnote). It’s about 15 euro and it’s well worth it. Almost all monitors use the PWM method as it is cheaper to manufacture, so unless you have a high-end one that specifically states it’s using DC dimming, you can assume you would benefit by dimming your screen via this app instead of the physical buttons located on the monitor itself.
Next to that it also has multiple handy features which I use all the time. It can for instance adjust your screen’s color balance based on the time of day. That way it blocks most of the blue light entering your eyes at night. Blue light in the evening disrupts your natural sleep rhythm. That’s a whole different and extensive subject, let me know if you want to know more as I can write up a separate article for that.
Also it helps me with taking (micro) breaks through it’s built in timer. Every 2 minutes my screen shows an overlay letting me know that I have to look away from the screen and focus on something in the distance. So that way my eyes can relax a little bit. You can of course change the timer to a longer interval which I imagine suites less visually challenged people 
I found this very helpful in extending the time I can spend doing computer stuff. Who knew that taking short breaks actually works 
Check out this TEDx presentation by Daniel Georgiev, the software engineer who created the Iris app for a further deep dive into the workings of modern monitors.
Last thing I considered when buying a new monitor is the screen’s finish. You may have noticed that some laptop screens have these high gloss finishes, which will increase the contrast and color vibrance. It looks really good, but the extra reflective surface makes it difficult to focus on the screen. You instead switch between focusing on the reflections and the stuff on the screen itself. My neuro-optometrist compared it to reading from a mirror.
The other option is called matte finish, which will almost be reflective free. Some manufacturers even let you choose between the two when buying a new monitor or laptop. So definitely a matte finish for me 😵
So to summarize my main takeaways
- High refresh rate, preferably 120 Hz or higher to reduce flicker and increase more natural motion
- Get a monitor with DC dimming or use a special program like Iris to control the brightness of your screen
- Opt for a matte screen finish to limit reflections
I ended up with a 27″ QHD monitor by LG (model: 27GL850). Besides a good refresh rate of 144Hz and DC dimming, it also comes highly recommended in other categories like color accuracy and ergonomics.
And Oh boy… I really should have bought this earlier. I now have a lot less headaches and I’m able to spend some time behind a computer for once. The higher refresh rate really makes a ton of difference for me. When I set the monitor to a lower refresh rate like 60Hz. The image looks way more “jittery” and uneasy. It’s actually a bit hard to describe.
So if you are experiencing any symptoms like headache, fatigue or other visual challenges after monitor use. It could be worthwhile to take a look at these three things in particular.
Ps. I did also check out e-paper monitors. Which would actually be perfect for me, as they use a completely different screen technology. Think e-reader screen, but bigger. Unfortunately, due to the high price and limited availability, they are currently not a viable option for me.
Let me know if you have any other suggestions for helping out the brain when using a monitor 
Iris, blue light filter and eye protection Software: https://iristech.co/
Hi Koert-Jan,
super interessant om te lezen. Ik ben vooral ook benieuwd naar het verschil tussen LCD en E-Ink, heb je daar informatie over of ervaring mee?
Thanks!
Hoi Jos, tussen die twee zitten (zoals je waarschijnlijk al weet) grote verschillen qua beeldtechniek.
Een van de grootste voordelen is dat een e-paper/ink scherm alleen een nieuwe beeld/frame laat zien als de content ook daadwerkelijk veranderd. Bij een traditioneel scherm (zoals LCD) gebeurt dat dus continue (ongeacht de content) met de snelheid van de verversingsfrequentie, bijv. 60 keer per seconde. Een e-paper/ink scherm creëert zo dus een veel rustiger beeld voor je ogen en brein.
Binnenkort hoop ik zo’n soort e-paper scherm tijdelijk te kunnen proberen, dus hoop daar dan wat meer inzicht over te kunnen geven 😃
Bedankt voor je bericht! Gr. Koert-Jan
Hi Koert-Jan,
dank je wel voor je reactie. Ik ben heel benieuwd naar je ervaringen met een E-Ink. Heel erg bedankt voor het uitzoeken en publiceren.
groet, Jos
Hi Koert-Jan,
wij zijn naar een nieuw scherm aan het kijken en willen ook een LG 27GL850 aanschaffen. Nu zie ik dat er ook een LG 27GL850 – B bestaat, ik kan niet goed vinden wat precies het verschil is anders dan dat het staat voor Bright. Ben jij iets tegengekomen hierover?
Tijdens het zoek kwam ik een review tegen (https://www.techspot.com/review/1908-lg-27gl850/) waar ook schermen met nog hogere Hz worden genoemd, heb jij die ook bekeken en is dat beter voor je of zijn er andere factoren die dat ook bepalen?
Alvast dank!
Hoi Jos, ten eerste excuus voor de late reply, de techniek liet mij even in de steek.
Die extra aanduiding is vaak een kleine variatie op het model, je kan het scherm met of zonder een geïntegreerde USB hub kopen. Op bol.com worden beide aangeboden en daarbij dan zie je ook het typenummer (met of zonder de – B) veranderen.
https://www.bol.com/nl/p/lg-27gn850-b-ultragear-qhd-nano-ips-gaming-monitor-144hz-27-inch/9300000005468213/?referrer=socialshare_pdp_www
Achterop mijn scherm staat trouwens ook LG 27GL850 – B als exacte type aanduiding. Ik vermoed dus dat dit het (enige) is, aangezien ik verder geen verschil kan ontdekken 😉
Ja ik heb veel verschillende schermen bekeken, waarbij het aantal Hz niet de enige beslissingsfactor was (resolutie, afmeting, kleur, kijkhoek, prijs etc. speelden ook mee). Die afweging zal dus voor iedereen anders zijn. Althans, ik denk dat je met dit scherm erg tevreden zal zijn, het is een goede alleskunner.
Succes en bedankt voor je vraag!