Redshift is a scientific software designed to save your eyes from strain due to prolonged exposure to the monitor. The reddish tint saves your eyes from the direct white glow of the monitor and is soothing to the eyes as well. Try it out! It is available in synaptic by default on Ubuntu. Remember that sometimes it even takes up to a few days to adjust your eyes to Redshift.
To install Redshift on Ubuntu:
$ sudo apt-get install redshift-gtk
Redshift configuration file is at ~/.config/redshift.conf.
To start Redshift, run: