[UPDATE: Now works for multiple connected outputs] I woke up around midnight with an urge to do some late night hacking, but I didn't want a bright monitor screwing up my body's circadian rhythm. I've heard that at night blue (short wavelength) lights are particularly bad for your diurnal clock. That may be a bunch of hooey, but it is true that redder (longer wavelength) colors are easier on my eyes at night. This command makes the screen dimmer and adjusts the gamma curves to improve contrast, particularly darkening blues and greens (Rɣ=2, Gɣ=3, Bɣ=4). To reset your screen to normal, you can run this command: xrandr | sed -n 's/ connected.*//p' | xargs -n1 -tri xrandr --output {} --brightness 1 --gamma 1:1:1 or, more briefly, xgamma -g 1 Note: The sed part is fragile and wrong. I'm doing it this way because of a misfeature in xrandr(1), which requires an output be specified but has no programmatic way of querying available outputs. Someone needs to patch up xrandr to be shell script friendly or at least add virtual outputs named "PRIMARY" and "ALL". . Todo: Screen should dim (gradually) at sunset and brighten at sunrise. I think this could be done with a self-resubmitting at job, but I'm running into the commandlinefu 127 character limit just getting the sunrise time: wget http://aa.usno.navy.mil/cgi-bin/aa_pap.pl --post-data=$(date "+xxy=%Y&xxm=%m&xxd=%d")"&st=WA&place=Seattle" -q -O- | sed -rn 's/\W*Sunrise\W*(.*)/\1/p' I hope some clever hacker comes up with a command line interface to Google's "OneBox", since the correct time shows up as the first hit when googling for "sunrise:cityname". . [Thank you to @flatcap for the sed improvement, which is much better than the head|tail|cut silliness I had before. And thank you to @braunmagrin for pointing out that the "connected" output may not be on the second line.] Show Sample Output

Redshift will adjust the color temperature and protects eye at night -b : will adjust the brightness

I'm not sure what apt this is, but it seems to work on most X screens, an is useful for saving power, and not straining your eyes Show Sample Output

xrandr --output <outputname> --brightness <value> If the driver of your graphics card supports it, then you can use xrandr. The following command lists the current configuration: xrandr --current --verbose If you want to change the configuration of an output, then you need the name of the output. This name is part of the output of xrandr --current, for example LVDS1. The brightness can be changed like this: xrandr --output <outputname> --brightness 0.8 Gamma: xrandr --output <outputname> --gamma 0.5:1.0:1.0

alias screen-brightness='xbacklight -set' alias screen-off='xset dpms force standby' alias screen-min='xbacklight -set 1' alias screen-max='xbacklight -set 100' alias screen-inc='xbacklight -inc 10' alias screen-dec='xbacklight -dec 10'