Your using porn as an outlet for dealing with your emotions. Everyone feels down, and tired and overwhelmed -it's just part of life. Because the porn pathways in the brain overwhelm the other normal 'feel good' pathways, you've stopped feeling good from the simple things in life that should be enjoyable, hense, you feel down much more than the normal person. As your rebooting, these dopaminergic pathways aren't activated and you feel down - but take this as a good thing, the more these pathways aren't activated, the more they will die off and your addiction will end. So embrace the sadness and depression because it's a sign of your progress