The Instant of Now by Irvin E. Cox

As the Vininese ship shot smoothly out into the night sky, Dirrul's surface jet slashed back toward the Agronian capital. A synthetic tension, which he deliberately fed with nightmare improbabilities, kept him reasonably alert until he had safely returned the jet to its place in the compound. Then weariness engulfed him. Groggily he staggered to the pneumotube and within five minutes he was asleep in the small two-room worker's apartment where he lived.

The insistent _ping_ of the door visiscope woke him. Dirrul glanced at his wall clock and saw that it was still early morning. He had slept less than three hours. Swearing angrily he turned down the visiarm. Dr. Kramer's serene aging white-bearded face was mirrored on the grey-tinted screen.