“Well then,” he said, running a hand through his hair and cutting his eyes anxiously towards the door. “I’ll leave you now. Hell of a thing that’s happened, good Lord. You must be feeling awfully rough. A good solid sleep will be the best thing in the world for you. Are you tired?” he said, looking at me closely. Was I? I was wide awake, and yet part of me was so glassed-off and numb I was practically in a coma.
The Goldfinch by Donna Tartt
What does glassed-off mean here? Is it along the line of 'detached, sequestered?