I don't think complete disconnection is important. What is important is what you are doing while you are connected during your personal time.
I used to have a hard time getting away from work. Now I don't check emails and I avoid programming on the weekend. If the servers melt someone will phone me. I used to find checking emails was stressful. Someone would report a small issue and the little thing would nag at me to fix it. I found it hard to relax.
One weekend I assumed the world wasn't going to end, I assumed my help wouldn't be required. I kept my phone with me. Been enjoying completely work free weekends ever since.
Maybe a day a week away from the world is a good idea, and with a family about all I can hope for :-)