Open console and type

bind n "pp_colormod_addb 34; pp_colormod_addg 209; pp_colormod_addr 0; pp_colormod_brightness -1.71; pp_colormod_mulb 0; pp_colormod_mulr 0; pp_colormod_mulg 0; pp_colormod_contrast 2.55; pp_colormod_color 0.07; pp_colormod 1"

Replace n with whatever key you want to press to enable your night vision. I use n because that's what it is from Counter-Strike: Source.

Press N. You have night-vision now.

Open console and type

bind m "pp_colormod 0"

Replace m with whatever key you want. I use m because it's right next to n, our toggle on key.

Press M. Your night vision is now off.

Open console and type

pp_colormod_addb 34; pp_colormod_addg 209; pp_colormod_addr 0; pp_colormod_brightness -1.71; pp_colormod_mulb 0; pp_colormod_mulr 0; pp_colormod_mulg 0; pp_colormod_contrast 2.55; pp_colormod_color 0.07

Press enter.

Then type

bind b "toggle pp_colormod 1 0"

Press B. Press B again. You have a toggle key now.

If you've done everything right, you now have some binds for night vision in Garry's Mod. I know it's sub-par and not always working how you'd expect, but I was screwing around with Color Modification and thought I'd share this. This is (should be) allowed on all servers of Garry's Mod, regardless of any variables or gamemode (MAYBE).

Edit (Jan 7, 2018): I cleaned up some stuff, mainly getting rid of the sounds since I found some issues. Also I’ve noticed something somewhere will cause your colormod to be set to some barely more red tint. If you have two separate binds, this isn’t an issue, but with the toggle bind, it is.

Thanks for reading!