The only way for you to live any long period of time is for the people in the real world to move you to a hospital and hook you up to machines. In the novels, they mention that while you can't remove the NervGear, you can lose your internet connection for up to 2 hours or so before the helmet fries your brain. During the time when you're disconnected, NervGear is probably still intercepting signals to your body, but you're probably unconscious.
I imagine they wait until nighttime to disconnect you and move your body to a hospital, in the hopes that you're not in the middle of a battle in-game.