If you are a programmer who have to stay long hours against a display, you will need always less light and more constast. This means you need a black background and white font color. To do this you need to create a Nopepad++ theme and install it after each NPP install. Instead of this I add my theme here; you just need to save it in C:\Program Files (x86)\Notepad++\themes\A1_Res_u_Spi.xml and restart/run your NPP as administrator once and in "settings->style configuration" change it to A1_Res_u_Spi.xml. See screenshot/attachment for look of that example.
Content of A1_Res_u_Spi.xml: