Saturday by Ian Mcewan

Excerpt from Saturday by Ian McEwan:
Some hours before dawn Henry Perowne, a neurosurgeon, wakes to find himself already in motion, pushing back the covers from a sitting position, and then rising to his feet. It's not clear to him when exactly he became conscious, nor does it seem relevant. He's never done such a thing before, but he isn't alarmed or even faintly surprised, for the movement is easy, and pleasurable in his limbs, and his back and legs feel unusually strong. He stands there, naked by the bed - he always sleeps naked - feeling his full height, aware of his wife's patient breathing and of the wintry bedroom air on his skin. That too is a pleasurable sensation. His bedside clock shows three forty. He has no idea what he's doing out of bed: he has no need to relieve himself, nor is he disturbed by a dream or some element of the day before, or even by the state of the world. It's as if, standing there in the darkness, he's materialised out of nothing, fully formed, unencumbered. He doesn't feel tired, despite the hour or his recent labours, nor is his conscience troubled by any recent case. In fact, he's alert and empty-headed and inexplicably elated. With no decision made, no motivation at all, he begins to move towards the nearest of the three bedroom windows and experiences such ease and lightness in his tread that he suspects at once he's dreaming or sleepwalking. If it is the case, he'll be disappointed. Dreams don't interest him; that this should be real is a richer possibility. And he's entirely himself, he is certain of it, and he knows that sleep is behind him: to know the difference between it and waking, to know the boundaries, is the essence of