Honestly I like working in a dark environment (Twilight on my all my editors), and recently I switched from a Windows to Linux (Ubuntu 16.04 with Unity Desktop on a PC). And being a night worker the brightness is a little harmful to my eyes. 

I searched for a bit and these were some of the commands I have tried so far after realizing that the GUI is just not giving me what I need - A Dimmer Screen.

```
$ dconf-editor

```

*A [snap](https://i.stack.imgur.com/t0zvi.png) of the values of the dconf-editor.*

```
$ add-apt-repository ppa:indicator-brightness/ppa
$ apt-get update
$ apt-get install indicator-brightness

```

*Nothing happened after toggling the new indicator.*

```
$ apt-get install xbacklight
$ xbacklight -set 40
$ xbacklight -set 20

```

*Enabled Xbacklight at [startup](https://i.stack.imgur.com/QCPO5.png)*

```
$ ls /sys/class/backlight/

```

**acpi\_video0**

*I dont seem to have intel\_backlight so I didn't do this last hack on my system.*

```
$ gedit /etc/rc.local
echo 900 > /sys/class/backlight/intel_backlight/brightness

```

I am a little lost. I would like to know if there is any tool that I can use to decrease the brightness on the system as a whole besides this or is there something that I am missing as a Noob user? 

I use Screen Dimmer for Firefox, Twilight for my Code Editors and the terminal is already black. It is the window applications like the File Viewer, Libre Office etc that needs to be dimmed down. I would consider getting a darker desktop theme also (if that is possible) as a valid answer. 

Thank-you for being patient enough to read through this rather unintentionally long question.