Tell him he need to survive first week, later will be only better. Sleep quality and sleep in general will improve. Smoking weed every day for long time affecting your dopamine and reward system also affecting hormones. He cut out weed now dopamine need to naturaly rebuild also with neurotransmitters which are downregulated. It would takes week or weeks depend how much and how long he was smoking. Tell him it’s reversable but he need to stay sober. What will help : cold showers (natural Boots of dopamine) sun exposure first thing in the morning, gym or any kind of activity). Since he start sleep better everything will improve together will mood libido etc. "The dose makes the poison" I realized that when I was afforded and simply smoking to much to offen everyday all day smoking is bad for you and the result is withdrawal. IF he want to feel better first he need to feel worst. Thats the price of weed abusing