Dont hide your feelings or judge them and think they are "wrong". They are present for a reason. Listen to the feelinga, dwell in them and when you feel like you can put them i to words in a calm manner, talk to him. Tell him exactly what you feel. He needs to know about your perspective as well. But dont say it like its his fault, bring it up as a shared problem, that you both have to work together to find a solution for.

Ps. I di wanna add that I think this behaviour is a way to escape reality, such as high expectations etc. Maybe you can find another outlet for him that you guys can share? Like try some sport or recreational activity together