I Worry About My Son Who Dropped Out of School and Has No Job

I’m a female part-time worker in my mid-50s suffering from an intractable disease. I would like advice about my son, who is in his late 20s and left home 2½ years ago and has not returned since. My son, who was a cheerful person, suddenly quit his part-time job in the summer of his third year at university and became absorbed in playing games on his smartphone, leading him to stay awake at night and sleep during the day. He also became unable to earn credits at the university.