The Six Fingers of Time by R. A. Lafferty, Science Fiction, Adventure (Hardcover)

He began by breaking things that morning. He broke the glass of water on his night stand. He knocked it crazily against the opposite wall and shattered it. Yet it shattered slowly. This would have surprised him if he had been fully awake, for he had only reached out sleepily for it.

Nor had he wakened regularly to his alarm; he had wakened to a weird, slow, low booming, yet the clock said six, time for the alarm. And the low boom, when it came again, seemed to come from the clock.

He reached out and touched it gently, but it floated off the stand at his touch and bounced around slowly on the floor. And when he picked it up again it had stopped, nor would shaking start it.

He checked the electric clock in the kitchen. This also said six o'clock, but the sweep hand did not move. In his living room the radio clock said six, but the second hand seemed stationary.

That was only the beginning. Worse things were to come -- much, "much" worse . . .