Implementation for Linux:

    #!/bin/bash
    set -e
    while true; do
        sleep 20m
        xlock -allowaccess&
        pid=$!
        sleep 20s
        kill $pid
    done

On the topic of eye strain. For anyone not familiar with f.lux, highly recommend you check it out. Everyone that I have recommended it to so far loves it. https://justgetflux.com

I've found f.lux indispensable for long hours of computer work, be it coding or reading. Surprised when I find friends who haven't installed it (or an alternative) yet -- this stuff should be standard, especially on incredibly bright-screen Macs. If you're on Linux, try Redshift instead.

When will something like this be available on my non-jailbroken iPhone? Heck, maybe someone could make a third-party browser app that tints itself ... turning down the brightness is just not the same.

There is also a Chrome App called Eye Care. It has slightly more flexibility and runs on Win/Mac/Linux

https://chrome.google.com/webstore/detail/eye-care/ingonfahm...

+1 for f.lux

I have experienced that eyes strain much lesser while using a LCD display instead of an LED display. Experienced this pretty much consistently. LEDs start hurting my eyes after some time.

And I use a MBP with Retina display for long hours - and I have to say, it has never put stress on my eyes at all (unless I make the screen too bright). Also I do not work at super-high small font resolutions - that allows me to keep distance from the screen. The only thing that I find better than it is Kindle reader.

Has the 20-20-20 rule actually been scientifically verified as the optimal regime for relieving eye strain or was it something thought up by some bloke off the top of his head?

Is this even usable as a developer?

Seems it'll be annoying for something to break my concentration every 20 minutes, losing my flow all the time.

Workrave is a great cross platform application for doing this.

I use Time Out for OS X, works like a charm:

http://www.dejal.com/timeout/

Sounds incredibly disruptive: http://heeris.id.au/2013/this-is-why-you-shouldnt-interrupt-...

After 20 minutes, when you may finally be reaching flow... "POP"...

Using coloured glasses works for me to limit eye strain.

If you use this, you might as well take the opportunity to stand up every 20 minutes.

Would like to see multiple screen support too..

Thanks a lot, it seems simple and useful.

Anything similar for OSX?