Man with No Name- Good Sleeper

He lay for a moment, listening to the groaning and crackling of Kirp’s bed, beyond the thin partition, then closed his eyes and was almost instantly asleep.

As always, the hunter awoke instantly and completely at the precise time he had fixed in his mind. He lay for a moment testing the darkness with his senses, then sat up. The storm had long since passed and the first pale glow of dawn touched the eastern sky.
...

The bounty hunter rolled over on his back, pillowed his head on crossed arms, tilted the flat-crowned hat over his eyes and was almost instantly asleep. He slept a precise eighteen minutes, then awoke as abruptly and fully as he had dropped off.

His timing was perfect. In the distance, the troop of bandits with their prisoner were just emerging from the rocky pass.

- Blood for a Dirty Dollar, chapters 12 and 13