The Deputy Director hardly ever slept. When it became absolutely necessary for him to do so, be took a drug, but the necessity was rare, for the mode of consciousness he experienced at most hours of day or night had long ceased to be exactly like what other men call waking. He had learned to withdraw most of his consciousness from the task of living, to conduct business, even, with only a quarter of his mind. Colours, tastes, smells, and tactual sensations no doubt bombarded bis physical senses in the normal manner: they did not now reach his ego. The manner and outward atttitude to men which he had adopted half a century ago were now an organisation which functioned almost independently like a gramophone and to which he could hand over his whole routine of interviews and committees. While the brain and lips carried on this work, and built up day by day for those around him the vague and formidable personality which they knew so well, his inmost self was free to pursue its own life. That detachment of the spirit, not only from the senses, but even from the reason, which has been the goal of some mystics, was now his.
Hence he was still, in a sense, awake-that is, he was certainly not sleeping – an hour after Frost had left him to visit Mark in his cell. Anyone who had looked into the study during that hour would have seen him sitting motionless at his table, with bowed head and folded hands. But his eyes were not shut. The face had no expression; the real man was far away suffering, enjoying, or inflicting whatever such souls do suffer, enjoy or inflict when the cord that binds them to the natural order is stretched out to its utmost but not yet snapped. [C S Lewis – That Hideous Strength]