Redshift shifts the color palette of the screen towards the red spectrum at nighttime (and undoes it during daylight). To dim as well the (external) screens on Linux hooks are called for; citing man redshift: Executables (e.g. scripts) placed in folder ~/.config/redshift/hooks will be run when a certain event happens. The first parameter to the script indicates the event and further parameters may indicate more details about the event. The event period-changed is indicated when the peri...