I'm going to have to try Unhook, YouTube distractions are one of my biggest.
The one I use is called LeechBlock, I can set block lists, time of use per unit of time (day, hour, etc), block times on specific days, I can even set it to lock me out of the settings during specific times so I can't easily change things when I'm block out of distractions.
It's on Firefox and Chrome, maybe others but I'm not sure.
Of course it can get really annoying but that's the point really, bother me enough to break the cycle of endlessly clicking the day away.